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The Cosmic Perspective, 7e (Bennett et al.) Chapter 1 A Modern View of the Universe 1.1 Multiple-Choice Questions 1) What is the meaning of the word cosmos? A) the origin of Earth and life upon it B) the light from a distant astronomical object C) the Milky Way D) the sum total of all matter and energy, that is, everything within and between all galaxies E) the dark sky Answer: D 2) Which of the following has your "address" in the correct order? A) you, Earth, solar system, Local Group, Local Supercluster, Milky Way B) you, Earth, solar system, Milky Way, Local Supercluster, Local Group C) you, Earth, solar system, Local Group, Milky Way, Local Supercluster D) you, Earth, Local Group, Local Supercluster, solar system, Milky Way E) you, Earth, solar system, Milky Way, Local Group, Local Supercluster Answer: E 3) About where is our solar system located within the Milky Way Galaxy? A) at the center of the galaxy B) about 10 percent of the way from the center of the galaxy to the outskirts of the galactic disk C) about two-thirds of the way from the center of the galaxy to the outskirts of the galactic disk D) near the far outskirts of the galactic disk E) in the halo of the galaxy above the galactic disk Answer: C 4) Roughly how many stars are in the Milky Way Galaxy? A) 1 billion B) 100 billion C) 10 billion D) 100 million E) 100 trillion Answer: B 5) Modern telescopes are capable of seeing bright galaxies up to about A) 1 million light-years away. B) 10 million light-years away. C) 1 billion light-years away. D) 10 billion light-years away. E) 1 trillion light-years away. Answer: D

6) Suppose we imagine the Sun to be about the size of a grapefruit. How big an area would the orbits of the eight planets of the solar system cover? A) the size of a typical dorm room B) the size of a typical campus building C) the size of a typical campus D) the size of a small city E) the size of a western state (e.g., Colorado) Answer: C 7) What do we mean when we say that the universe is expanding? A) Average distances are increasing between star systems within galaxies. B) Everything in the universe is gradually growing in size. C) Average distances are increasing between galaxies. D) The statement is not meant to be literal; rather, it means that our knowledge of the universe is growing. E) Individual galaxies are gradually growing in size. Answer: C 8) The age of the universe is A) between 10 million and 16 million years. B) between 100 million and 160 million years. C) between 1 billion and 1.6 billion years. D) between 10 billion and 16 billion years. E) between 100 billion and 160 billion years. Answer: D 9) How are galaxies important to our existence? A) Without galaxies, there could not have been a Big Bang. B) Without galaxies, the universe could not be expanding. C) Galaxies prevent planets from leaving their orbits around stars; e.g., our galaxy prevents Earth from leaving its orbit of the Sun. D) Galaxies recycle heavy elements produced in stars into future generations of stars. E) Galaxies provide the gravity that prevents us from falling off Earth. Answer: D 10) Earth is made mostly of metals and rocks. Where did this material come from? A) It was produced in the Big Bang. B) It was created by chemical reactions in interstellar space. C) It was produced by nuclear fusion in stars. D) It was made by our Sun. E) It was made by nuclear fission of uranium and other radioactive materials. Answer: C

11) What is nuclear fusion? A) an explosion caused by putting together two volatile chemicals B) the process of splitting nuclei to produce energy C) the process of turning matter into pure energy D) the process of combining lightweight nuclei to make heavier nuclei E) a process that only occurs in bombs Answer: D 12) Why did Carl Sagan say that we are star stuff? A) The composition of most stars (mostly hydrogen and helium) is about the same as the composition of our bodies. B) Cosmic rays reaching Earth from distant astronomical sources may be one source of mutations that help evolution along. C) Nearly every atom from which we are made once (before the solar system formed) was inside of a star. D) Nearly every atom from which we are made was once inside our star, the Sun. E) Sagan thought that all of us have the potential to be movie (or TV) stars like he was. Answer: C 13) Which of the following statements does not use the term light-year in an appropriate way? A) It's about 4 light-years from here to Alpha Centauri. B) It will take me light-years to complete this homework assignment. C) A light-year is about 10 trillion kilometers. D) It will take the Voyager spacecraft about 20,000 years to travel just 1 light-year. E) The Milky Way Galaxy is about 100,000 light-years in diameter. Answer: B 14) One light-hour is the distance that light travels in an hour. How far is this, in kilometers? (Recall that the speed of light is 300,000 km/s.) A) 300,000 km B) 18 million km C) 100 million km D) 1.08 billion km E) 9.46 trillion km Answer: D 15) Suppose we look at a photograph of many galaxies. Assuming that all galaxies formed at about the same time, which galaxy in the picture is the youngest? A) the one that is farthest away B) the one that is reddest in color C) the one that is bluest in color D) the one that is closest to us E) the one that appears smallest in size Answer: A

16) What do we mean by the observable universe? A) the part of the universe that we can see with the naked eye B) the part of the universe that we can see through telescopes C) the part of the universe that could be observed in principle, including things that may require future technologies D) the compendium of all objects that we have observed to date E) the entire universe, since it is inconceivable that there could be parts of the universe that we cannot observe Answer: C 17) Suppose we imagine the Sun to be about the size of a grapefruit. Which of the following describes the size and distance of Earth on the same scale? A) Earth is the size of a point about 1 meter away from the Sun. B) Earth is the size of a golf ball about 1 meter away from the Sun. C) Earth is the size of a point about 15 meters away from the Sun. D) Earth is the size of a golf ball about 15 meters away from the Sun. E) Earth is the size of a marble about 25 miles away from the Sun. Answer: C 18) What is the Sun mainly made of? A) hydrogen and oxygen B) hydrogen and helium C) carbon and nitrogen D) oxygen and carbon E) nearly equal portions of all the elements Answer: B 19) Which of the following is smallest? A) size of a typical planet B) 1 light-second C) 1 AU D) size of a typical star Answer: A 20) Which of the following is largest? A) size of a typical galaxy B) size of Pluto's orbit C) distance to the nearest star (other than our Sun) D) 1 light-year Answer: A

21) On the 1-to-10-billion scale, about how far is it to the nearest stars besides the Sun? A) 4 kilometers B) 400 kilometers C) 1,000 kilometers D) 4,400 kilometers E) 10,000 kilometers Answer: D 22) Suppose we imagine the Sun to be about the size of a grapefruit. How far away are the nearest stars (the three stars of Alpha Centauri)? A) the length of a football field B) 2.5 miles C) 250 miles D) 2,500 miles E) 25,000 miles Answer: D 23) If we use 1 millimeter to represent 1 light-year, how large in diameter is the Milky Way Galaxy? A) 100 millimeters B) 100 meters C) 1 kilometer D) 100 kilometers E) 1 million millimeters Answer: B 24) Which of the following best describes the Milky Way Galaxy? A) a spiral galaxy with a disk about 100,000 light-years in diameter and containing between 100 billion and 1 trillion stars B) a spiral galaxy with a disk about 1 billion kilometers in diameter and containing between 100 million and 1 billion stars C) a spiral galaxy with a disk about 100,000 light-years in diameter and containing about 100,000 stars D) a spherically shaped collection of stars including our solar system and about a dozen other solar systems, stretching about 4 light-years in diameter E) a spherically shaped collection of about 1 million stars that is about 100 light-years in diameter Answer: A 25) How long would it take to count all the stars in the Milky Way Galaxy at a rate of one star per second? A) several days B) several weeks C) several years D) several thousand years E) hundreds of thousands of years Answer: D 5 Copyright © 2014 Pearson Education, Inc.

26) How many galaxies are there in the observable universe? A) roughly (within a factor of 10) the same as the number of stars in our galaxy B) roughly a thousand times more than the number of stars in our galaxy C) about as many as the number of stars we see in the sky with our naked eyes D) about as many as the number of grains of sand on all the beaches on Earth E) an infinite number Answer: A 27) If you represented each star by a grain of sand, how much sand would it take to represent all the stars in the universe? A) all the sand in a typical playground sandlot B) all the sand on Miami Beach C) all the sand on the beaches of California D) all the sand on the beaches in the United States E) more than all the sand on all the beaches on Earth Answer: E 28) On the scale of the cosmic calendar, in which the history of the universe is compressed to 1 year, how long has human civilization (i.e., since ancient Egypt) existed? A) about half the year B) about a month C) a few hours D) a few seconds E) less than a millionth of a second Answer: D 29) On a cosmic calendar, in which the history of the universe is compressed into 1 year, when did the dinosaurs become extinct? A) in late December B) in late November C) in late October D) in late September E) in late August Answer: A 30) On a cosmic calendar, in which the history of the universe is compressed into 1 year, when did Kepler and Galileo first discover that we live on a planet in a solar system? A) 1 second ago B) 1 day ago C) 1 week ago D) December 25 E) December 30 Answer: A

31) On a cosmic calendar, in which the history of the universe is compressed into one year, how long is the average human life span? A) 0.2 millisecond B) 0.2 second C) 2 seconds D) 2 minutes E) 2 hours Answer: B 32) Approximately how fast are you moving with the rotation of Earth? A) 13,000 km/hr B) 1,300 km/hr C) 130 km/hr D) 13 km/hr E) not moving at all Answer: B 33) What is an astronomical unit? A) the average speed of Earth around the Sun B) the length of time it takes Earth to revolve around the Sun C) the average distance from Earth to the Sun D) the diameter of Earth's orbit around the Sun E) any basic unit used in astronomy Answer: C 34) Which of the following statements about the ecliptic plane is not true? A) It is the plane of Earth's orbit around the Sun. B) It is the plane of the Moon's orbit around Earth. C) During a solar eclipse, the Moon lies in the ecliptic plane. D) During a lunar eclipse, the Moon lies in the ecliptic plane. E) The nodes of the Moon's orbit lie in the ecliptic plane. Answer: B 35) Patterns of stars in constellations hardly change in appearance over times of even a few thousand years. Why? A) Stars are fixed and never move. B) Stars move, but they move very slowly–only a few kilometers in a thousand years. C) Although most stars move through the sky, the brightest stars do not, and these are the ones that trace the patterns we see in the constellations. D) The stars in our sky actually move rapidly relative to us–thousands of kilometers per hour– but are so far away that it takes a long time for this motion to make a noticeable change in the patterns in the sky. E) Stars within a constellation move together as a group, which tends to hide their actual motion and prevent the pattern from changing. Answer: D

36) How long does it take our solar system to complete one orbit around the Milky Way Galaxy? A) 10 thousand years B) 230 thousand years C) 1 million years D) 100 million years E) 230 million years Answer: E 37) Which of the following statements about the Milky Way Galaxy is not true? A) It contains between 100 billion and 1 trillion stars. B) Our solar system is located very close to the center of the Milky Way Galaxy. C) Our view of distant objects is obscured by gas and dust when we look into the galactic plane. D) The galaxy is about 100,000 light-years in diameter. E) One rotation of the galaxy takes about 200 million years. Answer: B 38) Which of the following correctly lists speeds from slowest to fastest? A) Earth's speed of revolution about the Sun, typical speeds of stars in the local solar neighborhood relative to us, Earth's speed of rotation on its axis, the speed of our solar system orbiting the center of the Milky Way Galaxy, the speeds of very distant galaxies relative to us B) Earth's speed of rotation on its axis, Earth's speed of revolution about the Sun, typical speeds of stars in the local solar neighborhood relative to us, the speed of our solar system orbiting the center of the Milky Way Galaxy, the speeds of very distant galaxies relative to us C) the speeds of very distant galaxies relative to us, typical speeds of stars in the local solar neighborhood relative to us, Earth's speed of rotation on its axis, Earth's speed of revolution about the Sun, the speed of our solar system orbiting the center of the Milky Way Galaxy D) the speed of our solar system orbiting the center of the Milky Way Galaxy, Earth's speed of revolution about the Sun, Earth's speed of rotation on its axis, the speeds of very distant galaxies relative to us, typical speeds of stars in the local solar neighborhood relative to us E) Earth's speed of revolution about the Sun, Earth's speed of rotation on its axis, the speed of our solar system orbiting the center of the Milky Way Galaxy, typical speeds of stars in the local solar neighborhood relative to us, the speeds of very distant galaxies relative to us Answer: B 39) Most of the mass in the Milky Way Galaxy is located A) in the halo (above/below the disk). B) within the disk. C) in the stars in the spiral arms. D) in the gas and dust. E) in the central bulge of the galaxy. Answer: A

40) The distribution of the mass of the Milky Way Galaxy is determined by A) counting the number of stars. B) determining the amount of gas and dust. C) studying how stars are distributed in the Milky Way. D) studying the rotation of the galaxy. E) weighing various parts of the Milky Way. Answer: D 41) From the fact that virtually every galaxy is moving away from us and more distant galaxies are moving away from us at a faster rate than closer ones, we conclude that A) the Milky Way Galaxy is expanding. B) we are located at the center of the universe. C) the farthest galaxies will eventually be moving faster than the speed of light. D) the universe is expanding. E) the universe is shrinking. Answer: D 42) By studying distant galaxies in the 1920s, Hubble made which of the following important discoveries that led us to conclude that the universe is expanding? A) All galaxies contain billions of stars, and all galaxies have spiral shapes. B) All galaxies were born at the same time, and all will die at the same time. C) All galaxies outside the Local Group are moving away from us, and the farther away they are, the faster they're going. D) All galaxies outside the Local Group are orbiting the Local Group. E) All galaxies outside the Local Group are moving away from us, and all are moving away at nearly the same speed. Answer: C 43) Imagine that we put a raisin cake into the oven, with each raisin separated from the others by 1 cm. An hour later, we take it out and the distances between raisins are 3 cm. If you lived in one of the raisins and watched the other raisins as the cake expanded, which of the following would you conclude? A) All raisins would be moving away from you at the same speed. B) More distant raisins would be moving away from you faster. C) More distant raisins would be moving away from you more slowly. D) It depends: If you lived in a raisin near the edge of the cake, you'd see other raisins moving away from you, but they'd be coming toward you if you lived in a raisin near the center of the cake. Answer: B

44) Which scientists played a major role in overturning the ancient idea of an Earth-centered universe, and about when? A) Copernicus, Kepler, and Galileo; about 400 years ago B) Aristotle and Copernicus; about 400 years ago C) Newton and Einstein; about 100 years ago D) Huygens and Newton; about 300 years ago E) Aristotle and Plato; about 2,000 years ago Answer: A 1.2 True/False Questions 1) Our solar system is located in the center of the Milky Way Galaxy. Answer: FALSE 2) The solar system contains about 100 billion stars. Answer: FALSE 3) A typical supercluster contains no more than about 10,000 stars. Answer: FALSE 4) One light-year is about 10 trillion kilometers. Answer: TRUE 5) In the grapefruit model of the solar system, it would take a few minutes to walk from the Sun to the inner edge of the Kuiper Belt (Pluto). Answer: TRUE 6) The observable universe is the same size today as it was a few billion years ago. Answer: FALSE 7) The Milky Way is moving further away from most other galaxies in the Universe. Answer: TRUE 8) No galaxies existed before the Big Bang. Answer: TRUE 9) Voyager 2 should reach the nearest stars (besides the Sun) in about 500 years. Answer: FALSE 10) Earth is always precisely 1 AU from the Sun. Answer: FALSE

1.3 Short Answer Questions 1) The speed of light is 300,000 km/s. How far is a light-year? Be sure to show all work clearly on your calculations. Answer: 1 light-year = (speed of light) × (1 yr) =

= 9,460,000,000,000 km 2) How big is Earth on the 1-to-10 billion scale described in Section 1.2. Answer: Scaled radius of Earth = actual radius / 1010 = 6,378 km / 1010 = 6,378 × 105 cm / 1010 = 6.378 × 108 cm / 1010 = 6.378 × 10-2 cm = 0.6 mm This is about the size of the tip of a (fine tip) ballpoint pen. 3) Briefly explain what we mean by the statement "The farther away we look in distance, the further back we look in time." Answer: It means that when we look at a distant object, we see it as it was some time in the past, rather than as it is now. This is because the light we see has taken time to travel from the object to us. 4) Starting from the Big Bang, briefly explain how our solar system came to contain the chemical elements necessary to make Earth and living organisms. Answer: The Big Bang produced hydrogen and helium. Over time, stars have converted about 2 percent of this material into heavier elements, including all the elements of which we and Earth are made. Stars expel this material through winds and explosions, and the galaxy recycles it into new generations of stars. When a new star system forms, it therefore contains the ingredients needed to make planets and living organisms. 5) Briefly explain why an expanding universe implies a beginning (called a Big Bang). Answer: The fact that the universe is expanding means the average distance between galaxies is growing, which implies that this average distance was smaller in the past. Extrapolating back in time, there must have been a time when the distance between galaxies (or their precursors) was zero, which must be the beginning of the universe. 6) Consider the following statement, and explain whether or not it is sensible: NASA hopes to build a new telescope that will allow us to see 100 million light-years into the past. Answer: Not sensible: It uses light-years as a length of time.

7) Consider the following statement, and explain whether or not it is sensible: NASA hopes to build a new telescope that will allow us to see some galaxies as they appeared 8 billion years ago. Answer: Sensible: By looking to a distance of 8 billion light-years, we can see objects as they looked 8 billion years ago. 8) Consider the following statement, and explain whether or not it is sensible: The universe is between 10 and 16 billion light-years old. Answer: This statement does not make sense because it uses the term light-year as a length of time, rather than as a distance. 9) Consider the following statement, and explain whether or not it is sensible: It will take me light-years to complete this homework assignment. Answer: This statement does not make sense because it uses the term light-year as a length of time, rather than as a distance. 10) Consider the following statement, and explain whether or not it is sensible: Someday we may build spaceships capable of traveling at a speed of 1 light-second per hour. Answer: This statement is fine. A light-second is 300,000 kilometers, so it simply says that we'll someday build spaceships that can travel at a speed of 300,000 km/hr. 11) Briefly explain how the Sun generates energy. Answer: The Sun generates energy through nuclear fusion in its core, converting hydrogen into helium. This process releases energy because a small amount of the mass of the hydrogen is converted to energy. 12) Imagine that you could drive your car in space. Assume that you can drive at a constant speed of 100 kilometers per hour. Suppose you started driving from the Sun. How long would it take, in years, to reach Earth? Answer: t =

= 1.5 million hours = 171 years

It would take about 171 years to drive from the Sun to Earth. 13) Explain why it is so difficult to see planets around other stars. Answer: Planets are very faint compared to the stars they orbit. Moreover, they are very close to their parent star compared to the distance between stars. On the 1-to-10 billion scale, where the Sun is the size of a grapefruit and Earth is a pinhead about 15 meters way, the nearest star is several thousand kilometers away. Together, this makes it extremely difficult to distinguish the faint light of a planet from the star it orbits. (Nevertheless, massive Jupiter-like planets have been indirectly detected orbiting around nearby stars.)

14) Based on the idea of "spaceship Earth," write one or two paragraphs explaining why it is not the case that we are "just sitting here." Answer: Far from just sitting still, we on Earth are moving relative to the Sun, planets, stars, and even other galaxies. The rotation of Earth causes the most noticeable changes in the sky. This motion around Earth's axis causes the Sun and stars to appear to rise and set, producing what we call a "day." The revolution of Earth about the Sun produces the monthly changes of the constellations, the seasonal weather changes due to Earth's tilt, and the parallax of some stars. The precession of Earth's axis, a very slow movement that has a period of 26,000 years, causes the movement of the North Star, and the changing position of the equinoxes and solstices. The motion of the Sun relative to the stars in the local solar neighborhood is at an extremely fast speed, although barely noticeable. Over time, this movement causes the patterns of the stars in the sky to change. The rotation of the galaxy means that the entire solar system is also orbiting the center of the Milky Way. This also produces motions of stars and clouds of gas. The expansion of the universe, the fact that the space between most galaxies is increasing with time, means that almost all galaxies outside the Local Group are moving away from us, with the more distant ones moving away faster. All of these motions, although not felt by us on Earth, are observed by watching the sky and prove that we are not "just sitting here." 15) How fast is the Moon orbiting Earth? Answer: From Appendix E, you can find that the distance from Earth to the Moon is 384.4 x 103 km and the orbital period of the Moon around Earth is 27.322 days. The orbital circumference is therefore 2 × π × 3.844 × 105 km ≈ 2.42 × 106 km, and the orbital period in hours is 27.322 × 24 ≈ 6.56 hours. Therefore, orbital speed = = ≈ 3700 km/hr 16) Consider the following statement, and explain whether or not it is sensible: Earth is always precisely 1 AU from the Sun. Answer: Not sensible: One AU is the average distance between Earth and the Sun. 17) Process of Science: Devise an experiment that would produce evidence (not necessarily proof) that Earth is round. You may use any technology you like, but you may not leave Earth (i.e., no satellite photos and no space travel). Be as creative as you like–there are many right answers. Answer: Some answers are: circumnavigate the globe; call a friend in Japan during the day here and find out that it's night there; watch the sails of ships sailing off into the distance; observe Polaris from the North Pole and watch its position change as you move towards the equator, etc.

18) Process of Science: Think of some ways in which you can demonstrate the following by simply looking at the sky: a) the Sun and stars lie beyond the Earth's atmosphere b) the stars are further away than the Moon Answer: a) The Sun and stars disappear behind clouds. That tells us that clouds, in our atmosphere, lie between us and the stars. b) As the Moon moves across the sky, it blocks out ("occults") stars. This tells us that the Moon lies between us and the stars. 19) Process of Science: Think about some ways in which we might figure out how old things are that last for much longer than a human lifetime. What about for things that last longer than humans have existed? Answer: For relatively recent events, we can look at the human historical record as written in books, painted on rocks, or just passed on orally from generation to generation. There are several such examples that pertain to astronomical phenomena such as comets and supernovae. In the case of events that happened before humans existed, we have to look at evidence in the Earth's geological record. An example is the iridium layer that suggests a massive explosion the spread ejecta around the globe. We can also use radioisotope dating where we use the known timescale for the decay of a radioactive element to measure the age of an object such as a meteorite. 1.4 Mastering Astronomy Reading Quiz 1) Which of the following is not a general difference between a planet and a star? A) Planets are smaller than stars. B) Planets are dimmer than stars. C) All planets are made of rock and all stars are made of gas. D) Planets orbit stars, while stars orbit the center of the galaxy. Answer: C 2) Our solar system consists of A) the Sun and all the objects that orbit it. B) the Sun and the planets, and nothing else. C) a few hundred billion stars, bound together by gravity. D) the Sun and several nearby stars, as well as the planets and other objects that orbit these stars. Answer: A 3) A typical galaxy is a A) collection of a few hundred million to a trillion or more stars, bound together by gravity. B) large, glowing ball of gas powered by nuclear energy. C) nearby object orbiting a planet. D) relatively small, icy object orbiting a star. Answer: A

4) Which of the following best describes what we mean by the universe? A) the sum total of all matter and energy B) a vast collection of stars that number as many as the grains of sand on all the beaches on Earth C) all the galaxies in all the superclusters D) The universe is another name for our Milky Way Galaxy. Answer: A 5) What do astronomers mean by the Big Bang? A) the event that marked the beginning of the expansion of the universe B) a gigantic explosion that blew all the galaxies in the universe to smithereens C) the explosion of a massive star at the end of its life D) the event that marked the birth of our solar system Answer: A 6) What do we mean when we say that the universe is expanding? A) Everything in the universe is gradually growing in size. B) Within galaxies, average distances between star systems are increasing with time. C) The statement is not meant to be literal; rather, it means that our knowledge of the universe is growing. D) Average distances between galaxies are increasing with time. Answer: D 7) Based on observations of the universal expansion, the age of the universe is about A) 14,000 years. B) 14 million years. C) 14 billion years. D) 14 trillion years. Answer: C 8) A television advertisement claiming that a product is light-years ahead of its time does not make sense because A) it doesn't specify the number of light-years. B) it uses "light-years" to talk about time, but a light-year is a unit of distance. C) a light-year is an astronomically large unit, so a product could not possibly be so advanced. D) light-years can only be used to talk about light. Answer: B 9) The term observable universe refers to A) that portion of the universe that we have so far photographed through telescopes. B) the portion of the universe that can be seen by the naked eye. C) the portion of the universe that is not hidden from view by, for example, being below the horizon. D) that portion of the universe that we can see in principle, given the current age of the universe. Answer: D

10) On a scale in which the distance from Earth to the Sun is about 15 meters, the distance from Earth to the Moon is A) small enough to fit within your hand. B) about 1 meter. C) about 5 meters. D) about 30 meters. Answer: A 11) On a scale where the Sun is about the size of a grapefruit and the Earth is about 15 meters away, how far away are the nearest stars besides the Sun? A) 100 meters B) about the distance across 50 football fields C) about the distance across the state of Delaware D) about the distance across the United States Answer: D 12) The number of stars in the Milky Way Galaxy is approximately A) a few hundred. B) a few hundred thousand. C) a few hundred billion. D) a few hundred million. Answer: C 13) An astronomical unit (AU) is A) any very large unit, such as a light-year. B) the average distance between Earth and the Sun. C) the current distance between Earth and the Sun. D) the average distance between any planet and the Sun. Answer: B 14) What is the ecliptic plane? A) the plane of Earth's orbit around the Sun B) the plane of Earth's equator C) the plane of the Sun's equator D) the plane of the Milky Way Galaxy Answer: A 15) How long does it take the Earth to complete one orbit around the Sun? A) one year B) one day C) one month D) one week E) The time it takes Earth to orbit the Sun changes significantly from one orbit to the next. Answer: A

1.5 Mastering Astronomy Concept Quiz 1) Which of the following has your "cosmic address" in the correct order? A) You, Earth, solar system, Local Group, Local Supercluster, Milky Way Galaxy, universe B) You, Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe C) You, Earth, Local Group, Local Supercluster, solar system, Milky Way Galaxy, universe D) You, Earth, solar system, Local Group, Milky Way Galaxy, Local Supercluster, universe E) You, Earth, Milky Way Galaxy, solar system, Local Group, Local Supercluster, universe Answer: B 2) Using the ideas discussed in your textbook, in what sense are we "star stuff"? A) The overall chemical composition of our bodies is about the same as that of stars. B) Movie stars and other people are all made of the same stuff, so we all have the potential to be famous. C) Nearly every atom from which we are made was once inside of a star. D) We could not survive without light from our star, the Sun. Answer: C 3) How are galaxies important to our existence? A) Without galaxies, there could not have been a Big Bang. B) Without galaxies, the universe could not be expanding. C) Deep in their centers, galaxies created the elements from which we are made. D) Galaxies recycle material from one generation of stars to the next, and without this recycling we could not exist. Answer: D 4) When we look at an object that is 1,000 light-years away we see it A) as it was 1,000 years ago. B) as it was 1,000 light-years ago. C) as it is right now, but it appears 1,000 times dimmer. D) looking just the same as our ancestors would have seen it 1,000 years ago. Answer: A 5) Suppose we look at two distant galaxies: Galaxy 1 is twice as far away as Galaxy 2. In this case, A) Galaxy 1 must be twice as big as Galaxy 2. B) we are seeing Galaxy 1 as it looked at an earlier time in the history of the universe than Galaxy 2. C) we are seeing Galaxy 1 as it looked at a later time in the history of the universe than Galaxy 2. D) Galaxy 2 must be twice as old as Galaxy 1. Answer: B

6) Suppose we make a scale model of our solar system, with the Sun the size of a grapefruit. Which of the following best describes what the planets would look like? A) The planets are all much smaller than the Sun. Four planets are within about 20 meters of the Sun, while the rest planets are spread much farther apart. B) The planets are all much smaller than the Sun and are spread out evenly over a distance about the length of a large classroom. C) The planets are all much smaller than the Sun. Four planets are located within a few centimeters of the Sun, and four planets are located at distances ranging up to about a meter. D) The planets range in size from about the size of a marble to the size of a baseball. They are spread out over a region about the size of a football field. Answer: A 7) If you could count stars at a rate of about one per second, how long would it take to count all the stars in the Milky Way Galaxy? A) several days B) several weeks C) several years D) several thousand years Answer: D 8) The total number of stars in the observable universe is about A) 100 billion. B) the same as the number of grains of sand in a school sandbox. C) the same as the number of grains of sand on all the beaches on Earth. D) the same as the number of atoms that make up the Earth. Answer: C 9) Where is our solar system located within the Milky Way Galaxy? A) very near the center of the galaxy B) at the far edge of the galaxy's visible disk C) roughly halfway between the center and the edge of the visible disk of the galaxy D) in the halo of the galaxy Answer: C 10) If we imagine the history of the universe compressed into one year, dinosaurs became extinct A) about 6 months ago. B) about 3 weeks ago. C) yesterday morning. D) about an hour ago. Answer: C 11) Relative to the age of the universe, how old is our solar system? A) It is about 1% as old as the universe. B) It is between about 5% and 10% as old as the universe. C) It is about one-third the age of the universe. D) It is nearly the same age as the universe. Answer: C 18 Copyright © 2014 Pearson Education, Inc.

12) How do the speeds at which we are moving with Earth's rotation and orbit compare to the speeds of more familiar objects? A) Earth's rotation carries most people around the axis faster than a commercial jet travels, and Earth's orbit carries us around the Sun faster than the Space Shuttle orbits Earth. B) Earth's rotation carries most people around the axis at about the speed of a commercial jet, and Earth's orbit carries us around the Sun at about the speed of a military jet. C) Earth's rotation carries most people around the axis at about the speed of a car on the freeway, and Earth's orbit carries us around the Sun at about the speed of a commercial jet. D) Earth's rotation carries most people around the axis at about the speed at which the Space Shuttle orbits Earth, and Earth's orbit carries us around the Sun at nearly the speed of light. Answer: A 13) Why do the patterns of the stars in our sky look the same from year to year? A) because the stars in the constellations are so far away B) because the stars in the constellations are not moving C) because the stars in the constellations all move at the same speeds and in the same directions, so they don't change their relative positions D) because the stars in the constellations move so slowly—typically about the speed of a snail— that their motions are not noticeable Answer: A 14) Astronomers infer that the universe is expanding because distant galaxies all appear to A) be growing in size. B) be moving away from us, with more distant ones moving faster. C) be made mostly of dark matter. D) rotate rapidly. Answer: B 15) Which statement about motion in the universe is not true? A) The mysterious dark matter is the fastest-moving material in the universe. B) Some stars in the Milky Way Galaxy are moving toward us and others are moving away from us. C) Except for a few nearby galaxies, all other galaxies are moving away from us. D) Your speed of rotation around Earth's axis is faster if you live near the equator than if you live near the North Pole. Answer: A 16) When did humans learn that the Earth is not the center of the universe? A) within the past 500 years B) about 2,500 years ago C) about 1,000 years ago D) We haven't; there is still considerable scientific debate about whether Earth is the center of the universe. Answer: A

The Cosmic Perspective, 7e (Bennett et al.) Chapter 2 Discovering the Universe for Yourself 2.1 Multiple-Choice Questions 1) How many stars can you see with your naked eye on a clear, moonless night from a dark location? A) fewer than a thousand B) a few thousand C) about ten thousand D) about a hundred thousand E) more than you could count in your lifetime Answer: B 2) Which of the following best describes the modern definition of a constellation? A) a region of the celestial sphere B) a pattern of bright stars in the sky C) a Greek mythological figure D) a collection of stars that are near one another in space E) a group of stars that all lie at about the same distance from Earth Answer: A 3) Which of the following statements about the celestial sphere is not true? A) When we look in the sky, the stars all appear to be located on the celestial sphere. B) Earth is placed at the center of the celestial sphere. C) The celestial sphere does not exist physically. D) The "celestial sphere" is just another name for our universe. E) From any location on Earth, we can see only half the celestial sphere at any one time. Answer: D 4) Which of the following statements about the celestial equator is true at all latitudes? A) It lies along the band of light we call the Milky Way. B) It represents an extension of Earth's equator onto the celestial sphere. C) It cuts the dome of your sky exactly in half. D) It extends from your horizon due east, through your zenith, to your horizon due west. E) It extends from your horizon due north, through your zenith, to your horizon due south. Answer: B 5) What is the ecliptic? A) when the Moon passes in front of the Sun B) the Moon's apparent path along the celestial sphere C) the constellations commonly used in astrology to predict the future D) the Sun's daily path across the sky E) the Sun's apparent path along the celestial sphere Answer: E

6) When we look into the band of light in our sky that we call the Milky Way, can we see distant galaxies? Why or why not? A) Yes, they appear as small, fuzzy patches on the other side of our galaxy. B) Yes, there are many other galaxies that we see inside the Milky Way. C) No, because the stars, gas, and dust of the Milky Way block us from seeing them. D) No, because there are only galaxies above and below the plane of the Milky Way. E) No, we cannot see any other galaxies from Earth. Answer: C 7) Which of the following correctly describes the meridian in your sky? A) a half-circle extending from your horizon due east, through your zenith, to your horizon due west B) a half-circle extending from your horizon due north, through your zenith, to your horizon due south C) a half-circle extending from your horizon due east, through the north celestial pole, to your horizon due west D) the point directly over your head E) the boundary between the portion of the celestial sphere you can see at any moment and the portion that you cannot see Answer: B 8) If it is midnight in New York, it is A) daytime in Sydney, Australia. B) midnight in Sydney, Australia. C) midnight in Los Angeles. D) midday in Rio de Janeiro, Brazil. E) midnight everywhere. Answer: A 9) How many arcseconds are in 1°? A) 60 B) 360 C) 3,600 D) 100 E) 10,000 Answer: C 10) Which of the following statements does not use the term angular size or angular distance correctly? A) The angular size of the Moon is about 1/2 degree. B) The angular distance between those two houses in the distance is 30°. C) The angular distance between those two bright stars in the sky is about 2 meters. D) The angular size of the Sun is about the same as that of the Moon. E) You can use your outstretched hand to estimate angular sizes and angular distances. Answer: C

11) What is a circumpolar star? A) a star that is close to the north celestial pole B) a star that is close to the south celestial pole C) a star that always remains above your horizon D) a star that makes a daily circle around the celestial sphere E) a star that is visible from the Arctic or Antarctic circles Answer: C 12) Which of the following statements about circumpolar stars is true at all latitudes? A) They are the stars close to the north celestial pole. B) They always remain above your horizon. C) They make relatively small circles, traveling clockwise around the north celestial pole. D) Like all other stars, they rise in the east and set in the west. E) You cannot see them from the Southern Hemisphere. Answer: B 13) We describe a position on Earth's surface by stating its A) altitude and azimuth. B) altitude and direction. C) latitude and direction. D) latitude and longitude. E) meridian and longitude. Answer: D 14) What makes the North Star, Polaris, special? A) It is the brightest star in the sky. B) It is the star straight overhead. C) It appears very near the north celestial pole. D) It is the star directly on your northern horizon. E) It can be used to determine your longitude on Earth. Answer: C 15) You are standing on Earth's equator. Which way is Polaris, the North star? A) 30 degrees up, due West B) on the northern horizon C) directly overhead D) The answer depends on whether it's winter or summer. E) The answer depends on what time of day (or night) it is. Answer: B 16) By locating the north celestial pole (NCP) in the sky, how can you determine your latitude? A) The altitude of the NCP is the same as your latitude. B) The altitude of the NCP is your angular distance from the North Pole. C) The azimuth of the NCP is the same as your latitude. D) The azimuth of the NCP is the angular distance from the North Pole. E) The altitude of the NCP is the same as your distance from the North Pole. Answer: A 3 Copyright © 2014 Pearson Education, Inc.

17) Orion is visible on winter evenings but not summer evenings because of A) interference from the full Moon. B) the tilt of Earth's axis. C) the location of Earth in its orbit. D) the precession of Earth's axis. E) baseball on television. Answer: C 18) Why do we have seasons on Earth? A) As Earth goes around the Sun and Earth's axis remains pointed toward Polaris, the Northern and Southern hemispheres alternately receive more and less direct sunlight. B) The tilt of Earth's axis constantly changes between 0 and 23 1/2°, giving us summer when Earth is tilted more and winter when it is straight up. C) Earth's distance from the Sun varies, so that it is summer when we are closer to the Sun and winter when we are farther from the Sun. D) Seasons are caused by the influence of the planet Jupiter on our orbit. Answer: A 19) Why is it summer in the Northern Hemisphere when it is winter in the Southern Hemisphere? A) The Northern Hemisphere is closer to the Sun than the Southern Hemisphere. B) The Northern Hemisphere is "on top" of Earth and therefore receives more sunlight. C) The Northern Hemisphere is tilted toward the Sun and receives more direct sunlight. D) The Northern Hemisphere is tilted away from the Sun and receives more indirect sunlight. E) It isn't: both hemispheres have the same seasons at the same time. Answer: C 20) Which of the following statements is true? A) Both the Northern and Southern hemispheres receive the same amount of sunlight on the equinoxes. B) Both the Northern and Southern hemispheres receive the same amount of sunlight on the solstices. C) The Northern Hemisphere receives the most direct sunlight on the summer solstice. D) The Southern Hemisphere receives the most direct sunlight on the summer solstice. E) Both A and C are true. Answer: E 21) Which of the following statements about constellations is false? A) There are only 88 official constellations. B) Some constellations can be seen from both the Northern and Southern hemispheres. C) Some constellations can be seen in both the winter and summer. D) It is possible to see all the constellations from Earth's equator. E) Most constellations will be unrecognizable hundreds of years from now. Answer: E

22) Which of the following statements about lunar phases is true? A) The time between new Moons is two weeks. B) The time from one new Moon to the next new Moon is the same as the time from first-quarter Moon to third-quarter Moon. C) The full Moon sometimes rises around midnight. D) It is possible to have two full Moons during January, but not during February. E) It is possible to have two full Moons during November, but not during December. Answer: D 23) Which of the following is not a phase of the Moon? A) first-quarter Moon B) third-quarter Moon C) half Moon D) new Moon E) full Moon Answer: C 24) When someone on Earth observes the Moon in the first-quarter phase, someone on the Moon facing Earth observes Earth in the A) new Earth phase. B) first-quarter Earth phase. C) crescent Earth phase. D) third-quarter Earth phase. E) full Earth phase. Answer: D 25) If the Moon is setting at 6 A.M., the phase of the Moon must be A) first quarter. B) third quarter. C) full. D) new. E) waning crescent. Answer: C 26) If the Moon is setting at noon, the phase of the Moon must be A) full. B) first quarter. C) third quarter. D) waning crescent. E) waxing crescent. Answer: C

27) If the Moon is rising at midnight, the phase of the Moon must be A) full. B) first quarter. C) third quarter. D) waning crescent. E) waxing crescent. Answer: C 28) At approximately what time would a full Moon be on your meridian? A) 6 A.M. B) 9 A.M. C) noon D) 6 P.M. E) midnight Answer: E 29) At approximately what time would a first quarter Moon rise? A) 6 A.M. B) 9 A.M. C) noon D) 6 P.M. E) midnight Answer: C 30) If the Moon rises around 3 A.M., its phase must be A) full. B) first quarter. C) third quarter. D) waning crescent. E) waxing crescent. Answer: D 31) In which direction does a quarter Moon rise? A) north B) south C) east D) west E) The Moon becomes a quarter Moon only after it has risen and changed phase. Answer: C 32) Why do we see essentially the same face of the Moon at all times? A) because the other face points toward us only at new Moon, when we can't see the Moon B) because the Moon does not rotate C) because the Moon's rotational and orbital periods are equal D) because the Sun illuminates only one half at a time E) because the Moon has a nearly circular orbit around Earth Answer: C 6 Copyright © 2014 Pearson Education, Inc.

33) Which of the following statements about the Moon is true? A) The Moon goes through a cycle of phases because it always has the same side facing Earth. B) If you see a full Moon from North America, someone in South America would see a new Moon. C) The Moon's distance from Earth varies during its orbit. D) The Moon is visible only at night. E) The side of the Moon facing away from Earth is in perpetual darkness. Answer: C 34) Suppose you live on the Moon. How long is a day (i.e., from sunrise to sunrise)? A) 23 hours 56 minutes B) 24 hours C) a lunar month D) a year E) about 18 years Answer: C 35) Ashen light (or earthshine) is A) sunlight reflected by Earth that illuminates the "dark" portion of the Moon. B) the sunlight that shines on the face of the Moon that we never see. C) the light from the Moon that illuminates Earth's surface at night. D) the light we see at dawn just before the Sun rises. E) the light we see at dusk just after the Sun sets. Answer: A 36) All of the following statements are true. Which one explains the reason why there is not a solar eclipse at every new Moon? A) The nodes of the Moon's orbit precess with an 18-year period. B) The orbital plane of the Moon is tilted by about 5° to the ecliptic plane. C) The Moon rotates synchronously with its revolution about Earth. D) The sidereal month is shorter than the lunar month. E) The Moon is the primary cause of tides on Earth. Answer: B 37) What effect or effects would be most significant if the Moon's orbital plane were exactly the same as the ecliptic plane? A) Solar eclipses would be much rarer. B) Solar eclipses would be much more frequent. C) Solar eclipses would last much longer. D) both A and C E) both B and C Answer: B

38) What conditions are required for a solar eclipse? A) The phase of the Moon must be new, and the nodes of the Moon's orbit must be nearly aligned with Earth and the Sun. B) The phase of the Moon must be full, and the nodes of the Moon's orbit must be nearly aligned with Earth and the Sun. C) The phase of the Moon can be new or full, and the nodes of the Moon's orbit must be nearly aligned with Earth and the Sun. D) The phase of the Moon must be new, and the Moon's orbital plane must lie in the ecliptic. E) The phase of the Moon must be full, and the Moon's orbital plane must lie in the ecliptic. Answer: A 39) What conditions are required for a lunar eclipse? A) The phase of the Moon must be new, and the nodes of the Moon's orbit must be nearly aligned with Earth and the Sun. B) The phase of the Moon must be full, and the nodes of the Moon's orbit must be nearly aligned with Earth and the Sun. C) The phase of the Moon can be new or full, and the nodes of the Moon's orbit must be nearly aligned with Earth and the Sun. D) The phase of the Moon must be new, and the Moon's orbital plane must lie in the ecliptic. E) The phase of the Moon must be full, and the Moon's orbital plane must lie in the ecliptic. Answer: B 40) In addition to the conditions required for any solar eclipse, what must also be true in order for you to observe a total solar eclipse? A) Earth must lie completely within the Moon's umbra. B) Earth must lie completely within the Moon's penumbra. C) Earth must be near aphelion in its orbit of the Sun. D) The Moon's umbra must touch the area where you are located. E) The Moon's penumbra must touch the area where you are located. Answer: D 41) If part of the full Moon passes through Earth's umbra, we will see a(n) A) total lunar eclipse. B) penumbral lunar eclipse. C) partial lunar eclipse. D) partial solar eclipse. E) annular eclipse. Answer: C 42) If the Moon is relatively far from Earth, so that the umbra does not reach Earth, someone directly behind the umbra will see A) a penumbral lunar eclipse. B) a partial lunar eclipse. C) a partial solar eclipse. D) an annular eclipse. E) no eclipse. Answer: D 8 Copyright © 2014 Pearson Education, Inc.

43) When are eclipse seasons? A) in the spring and fall B) in the summer and winter C) when the nodes of the Moon's orbit are nearly aligned with the Sun D) when Earth, the Sun, and the Moon are exactly aligned for an eclipse E) during an eclipse Answer: C 44) The precession of the Moon's nodes means that A) there is a lunar eclipse every 6 months. B) there is a solar eclipse every 6 months. C) the eclipse seasons occur less than 6 months apart. D) the vernal equinox will be in Aquarius in a few hundred years. E) there are never two solar eclipses in the same year. Answer: C 45) What is the Saros cycle? A) the roughly 6-month period between eclipse seasons B) the 18-year cycle over which the pattern of eclipses repeats C) the period between total solar eclipses D) the period between a total solar eclipse and a total lunar eclipse E) the period between eclipses Answer: B 46) Ancient people who knew the Saros cycle could A) completely predict every lunar eclipse. B) completely predict every solar eclipse. C) predict what type of eclipse would occur. D) predict when they'd see the next total solar eclipse in their area. E) predict when an eclipse would happen, but not necessarily what type and where it would be visible. Answer: E 47) What happens during the apparent retrograde motion of a planet? A) The planet rises in the west and sets in the east. B) The planet appears to move westward with respect to the stars over a period of many nights. C) The planet moves backward through the sky over the course of a night. D) The planet moves backward in its orbit around the Sun. E) The planet moves through constellations that are not part of the zodiac. Answer: B

48) Why are lunar eclipses more commonly seen than solar eclipses? A) Lunar eclipses occur at night and are easier to see. B) The Moon goes around the Earth faster than the Earth goes around the Sun. C) The Earth casts a bigger shadow than the Moon. D) The tilt of the Moon's axis is smaller than the Earth's. E) The Moon is much closer to the Earth than the Sun. Answer: C 49) What causes the apparent retrograde motion of the planets? A) As Earth passes another planet, its gravitational pull slows down the other planet so that it appears to be traveling backward. B) When planets are farther from the Sun, they move slower than when they are nearer the Sun; it is during this slower period that they appear to move backwards. C) The other planets never really appear to move backward; the background stars shift due to Earth's revolution around the Sun. D) As Earth passes another planet, the other planet appears to move backward with respect to the background stars, but the planet's motion does not really change. E) Apparent retrograde motion is an illusion created by turbulence in Earth's atmosphere. Answer: D 50) Which of the following never goes in retrograde motion? A) the Sun B) Venus C) Mars D) Jupiter E) Saturn Answer: A 51) Which of the following statements about parallax is not true? A) You can demonstrate parallax simply by holding up a finger and looking at it alternately from your left and right eyes. B) The existence of stellar parallax is direct proof that Earth orbits the Sun. C) Measurement of stellar parallax allows us to determine distances to nearby stars. D) The technique of stellar parallax was used by Hubble to determine that the Andromeda Galaxy (M 31) is about 2 million light-years away. E) Ancient astronomers were unable to measure parallax and used the absence of observed parallax as an argument in favor of an Earth-centered universe. Answer: D 52) Which of the following statements about stellar parallax is true? A) We observe all stars to exhibit at least a slight amount of parallax. B) Stellar parallax was first observed by ancient Greek astronomers. C) The amount of parallax we see depends on how fast a star is moving relative to us. D) It takes at least 10 years of observation to measure a star's parallax. E) The closer a star is to us, the more parallax it exhibits. Answer: E 10 Copyright © 2014 Pearson Education, Inc.

53) We can't detect stellar parallax with naked-eye observations. Which of the following would make parallax easier to observe? A) increasing the size of Earth's orbit B) speeding up Earth's rotational motion C) slowing down Earth's rotational motion D) speeding up the precession of Earth's axis E) getting away from streetlights Answer: A 54) Why were ancient peoples unable to detect stellar parallax? A) They did not look for it. B) They could not see distant stars. C) They did not have the ability to measure very small angles. D) They did not observe for long enough periods of time. E) They did detect it, but they rejected the observations. Answer: C 2.2 True/False Questions 1) In South Africa, it's usually quite warm around the time of the winter solstice and quite cool around the time of the summer solstice. Answer: TRUE 2) Columbus was the first person to discover that Earth is round. Answer: FALSE 3) You can find the tilt of Earth's axis by measuring the angle between your horizon and the North Star. Answer: FALSE 4) The Milky Way can be seen only from the Northern Hemisphere. Answer: FALSE 5) The seasons on Earth are caused by its elliptical orbit around the Sun. Answer: FALSE 6) At midnight it is sometimes possible to observe the crescent Moon on the meridian. Answer: FALSE 7) It is possible to see the third-quarter Moon near the western horizon at sunrise. Answer: FALSE 8) It is possible to see the full Moon rising just before sunrise. Answer: FALSE 9) If you lived on the Moon, you'd see full Earth when we see new Moon. Answer: TRUE 11 Copyright © 2014 Pearson Education, Inc.

10) It is possible to view the Moon in first-quarter phase the day after a total lunar eclipse. Answer: FALSE 11) The Moon and the Sun are approximately the same angular size. Answer: TRUE 12) A solar eclipse occurs only when the Moon is new. Answer: TRUE 13) A lunar eclipse occurs only when the Moon is new. Answer: FALSE 14) Lunar eclipses are more commonly seen than solar eclipses. Answer: TRUE 15) Process of Science: Because we do not see stellar parallaxes with our eyes, we conclude that the Earth is at the center of the Solar System. Answer: FALSE 2.3 Short Answer Questions Choose the letter for the real motion of space from the list below that is responsible for the apparent motion of space as seen from Earth. A. Earth rotates once each day. B. Earth revolves around the Sun once each year. C. The direction of Earth's axis in space precesses with a period of 26,000 years. D. Stars appear to move randomly in the local solar neighborhood. E. The universe is expanding. 1) Polaris will no longer be the North Star 1,000 years from now. Answer: C 2) In the year A.D. 15,000, Vega will be a better north star than Polaris. Answer: C 3) The Big Dipper will look different 100,000 years from now than it does today. Answer: D 4) The Moon rises in the east and sets in the west. Answer: A 5) The stars of Orion's belt rise in the east and set in the west. Answer: A 6) A million years from now, Alpha Centauri will no longer be the nearest star system to our own. Answer: D 12 Copyright © 2014 Pearson Education, Inc.

7) If Earth's axis had no tilt, would we still have seasons? Why or why not? Answer: We would no longer have seasons, because the Sun's light would hit at the same angle all throughout the year, depending only on where you lived. The slight change in distance between Earth and the Sun during the year would not produce much of an effect. 8) Consider the following statement, and explain whether or not it is sensible: If you had a very fast spaceship, you could travel to the celestial sphere in about 100 years. Answer: This statement does not make sense because the celestial sphere is a concept and not a physical object. 9) Consider the following statement, and explain whether or not it is sensible: When I looked into the dark fissure of the Milky Way with my binoculars, I saw what must have been a cluster of distant galaxies. Answer: This statement does not make sense because we cannot see through the band of light we call the Milky Way to external galaxies; the dark fissure is gas and dust blocking our view. 10) Why does the Milky Way appear as a band of light in the sky? Answer: The solar system lies in the outer parts of the thin disk of a spiral galaxy. Thus when we look along the plane of the disk, we see large numbers of stars that, to the naked eye, merge into a band of light. When we look out of the plane of the disk, there are very few stars and the night sky is much darker. 11) Consider the following statement, and explain whether or not it is sensible: Although all the known stars appear to rise in the east and set in the west, we might someday discover a star that will appear to rise in the west and set in the east. Answer: This statement does not make sense. The stars aren't really rising and setting, they only appear to rise in the east and set in the west because the Earth rotates. 12) At what altitude and in what direction in your sky does the north or south celestial pole appear? Answer: Answers will vary with your latitude; latitude = altitude of NCP (or SCP in Southern Hemisphere). 13) Consider the following statement, and explain whether or not it is sensible: My sign is Ursa Major because the Sun was in Ursa Major when I was born. Answer: Not sensible: The Sun appears only in the constellations of the zodiac–and Ursa Major is not one of these. 14) Consider the following statement, and explain whether or not it is sensible: Last night I saw Jupiter in the constellation Ursa Major. Answer: This statement does not make sense because Jupiter, like all the planets, is always found very close to the ecliptic in the sky. The ecliptic passes through the constellations of the zodiac, so Jupiter can appear to be only in one of the 12 zodiac constellations–and Ursa Major is not one of these.

15) Answer each of the following questions for our local sky. A. Where is the north celestial pole in our sky? B. Is Polaris a circumpolar star in our sky? Explain. C. Describe the meridian in our sky. D. Describe the celestial equator in our sky. Answer: A. Answers will vary with latitude; here is a sample for 40°N: The north celestial pole appears at an altitude of 40°, in the direction due north. B. Yes, for any location in the Northern Hemisphere; no, for any location in the Southern Hemisphere. Polaris is circumpolar because it never rises or sets in our sky. It makes a daily circle, less than 1° in radius, around the north celestial pole. C. The meridian is a half-circle that stretches from the due south point on the horizon, through the zenith, to the due north point on the horizon. D. Answers will vary with latitude; here is a sample answer for 40°N: The celestial equator is a half-circle that stretches from the due east point on the horizon, through an altitude of 50° due south, to the due west point on the horizon. 16) Consider the following statement, and explain whether or not it is sensible: If you lived on the Moon, you'd see full Earth when we see new Moon. Answer: This is true, because at full Moon, Earth lies between the Sun and the Moon. Thus, an observer on the Moon would be looking at the night side of Earth. 17) Suppose you lived on the Moon near the center of the face that we see from Earth. During the phase of full Moon, what phase would you see for Earth? Would it be day or night at your home? Answer: During the full Moon, it would be daytime and you would see the phase of new Earth. 18) Suppose you lived on the Moon near the center of the face that we see from Earth. During the phase of new Moon, what phase would you see for Earth? Would it be day or night at your home? Answer: During the new Moon, it would be nighttime and you would see the phase of full Earth. 19) Suppose you lived on the Moon near the center of the face that we see from Earth. At what phase of the Moon would you see sunset? What phase of Earth would you see at this time? Answer: Sunset would occur at the Moon's first-quarter phase. You would see Earth in thirdquarter phase at this time. 20) Suppose you lived on the Moon near the center of the face that we see from Earth. At what phase of the Moon would you see sunrise? What phase of Earth would you see at this time? Answer: Sunrise would occur at the Moon's third-quarter phase. You would see Earth in firstquarter phase at this time. 21) What would you see if you were on the Moon during a lunar eclipse? Answer: During a lunar eclipse, you would see Earth pass in front of the Sun. It would be completely dark where you were.

22) Why is the Moon not completely invisible (it appears as a very deep red color) to the naked eye during a total lunar eclipse? Answer: The Moon shines through reflected light from the Sun and thus it becomes very dark during a lunar eclipse since the Moon lies within Earth's shadow at this time. However, some sunlight still gets through because it is bent (similar to the way a lens works) by Earth's atmosphere. We see the reflection of this faint light and thus the Moon is not completely invisible. (The bending of light is called refraction and the effect is strongest at long wavelengths. Thus it is most pronounced for red light and the eclipsed Moon appears dark red.) 23) What would you see if you were on the Moon during a solar eclipse? Answer: During a solar eclipse, you would see a small circular shadow traveling across a portion of Earth's surface. 24) Suppose the distance to the Moon were twice its actual value. Could we still have solar eclipses? If so, what type(s)? Answer: If the Moon were twice its actual distance from us, we would no longer be able to see total solar eclipses because the Moon would not be able to completely cover the surface of the Sun; however, we would still see partial and annular eclipses, although the Moon would not block as much of the Sun during these times. 25) Consider the following statement, and explain whether or not it is sensible: Last night I saw Mars move westward through the sky in its apparent retrograde motion. Answer: This statement does not makes sense because the apparent retrograde motion is noticeable only over many nights, not during a single night. (Of course, like all celestial objects, Mars moves from east to west over the course of every night.) 26) If, from the point of view of Earth-bound observers, the Moon is in new Moon phase on a particular day, what phase is Earth as seen from the Moon? Answer: full Earth 27) Process of Science: Your friend hypothesizes that the phases of the Moon are produced by Earth's shadow being cast on the Moon's surface. Devise an experiment to prove your friend wrong. Describe an observation you will make (time of day/night, location in sky) and describe what you will see that will clearly demonstrate that your friend's idea cannot be correct. Answer: If you observe any time when the Moon and Sun are both in the sky (e.g., in the daytime during a crescent Moon), you can clearly see that Earth's shadow cannot be cast on the Moon, as it is on the other side of Earth, where the Moon is not. Similarly, an observation of the full Moon shows the opposite: no Earth shadow at all, though the alignment would favor one. If the full Moon occurred when Earth's shadow could not hit it, it should be seen in the daytime, not at night–and then it would have no light source. 28) Process of Science: How could you show that the seasons depend on the tilt of the Earth rather than the distance the Earth is from the Sun? Answer: You could fly across the equator to see that there can be winter in one hemisphere at the same time there is summer in the other.

2.4 Mastering Astronomy Reading Quiz 1) About how many stars are visible to the naked eye on a clear, dark night away from city lights? A) a few dozen B) a couple thousand C) several million D) a few hundred billion Answer: B 2) What do astronomers mean by a constellation? A) A constellation is a region in the sky as seen from Earth. B) A constellation is a group of stars related through an ancient story. C) A constellation is any random grouping of stars in the sky. D) A constellation is a group of stars that are all located in about the same place in space. Answer: A 3) What is the ecliptic? A) the path the Sun appears to trace around the celestial sphere each year B) the Sun's daily path from east to west in our sky C) the path traced by the Moon's shadow on Earth during a solar eclipse D) a half-circle extending from your horizon due north, through your zenith, to your horizon due south Answer: A 4) What is the celestial sphere? A) The celestial sphere is a representation of how the entire sky looks as seen from Earth. B) The celestial sphere is a model that shows the true locations in space of the Sun and a few thousand of the nearest stars. C) The celestial sphere is a model of how the stars are arranged in the sky relative to our Sun, which is in the middle of the sphere. D) It represents a belief in an Earth-centered universe, and hence is no longer considered to have any use. Answer: A 5) What do we mean when we talk about the Milky Way in our sky? A) the patchy band of light that outlines the plane of the Milky Way Galaxy as seen from Earth B) the whitish patch of light we see when we look toward the center of the Milky Way Galaxy C) the spiral-shaped galaxy in which we live D) the bright stars of the constellations that lie along the ecliptic in our sky Answer: A

6) Which of the following statements does not use the term angular size or angular distance correctly? A) The angular distance between those two houses in the distance is 30 degrees. B) The angular distance between those two bright stars in the sky is about 2 meters. C) The angular size of the Sun is about the same as that of the Moon. D) You can use your outstretched hand against the sky to estimate angular sizes and angular distances. Answer: B 7) Which of the following correctly describes the meridian in your local sky? A) a half-circle extending from your horizon due east, through your zenith, to your horizon due west B) a half-circle extending from your horizon due east, through the north celestial pole, to your horizon due west C) a half-circle extending from your horizon due north, through your zenith, to your horizon due south D) the point directly over your head Answer: C 8) The point directly over your head is called A) the meridian. B) the zenith. C) the north celestial pole. D) the North Star. Answer: B 9) Stars that are visible in the local sky on any clear night of the year, at any time of the night, are called A) bright. B) seasonal. C) circumpolar. D) celestial. Answer: C 10) We describe a location on Earth's surface by stating its A) altitude and direction (or azimuth). B) meridian and longitude. C) latitude and direction. D) latitude and longitude. Answer: D

11) If you are located in the Northern Hemisphere, which of the following correctly describes a relationship between the sky and your location? A) The altitude of the north celestial pole equals your latitude. B) The altitude of the celestial equator equals your latitude. C) The altitude of the north celestial pole equals your longitude. D) The longitude of the north celestial pole is circumpolar, and therefore crosses your zenith at the meridian. Answer: A 12) Which of the following best describes why we have seasons on Earth? A) The tilt of Earth's axis causes different portions of the Earth to receive more or less direct sunlight at different times of year. B) Earth's elliptical orbit means we are closer to the Sun and therefore receive more intense sunlight at some times of year than at others. C) The tilt of Earth's axis causes the northern hemisphere to be closer to the Sun than the southern hemisphere in summer, and visa versa in winter. D) The varying speed of Earth in its orbit around the Sun gives us summer when we are moving fastest and winter when we are moving slowest. Answer: A 13) Each choice below describes how a few astronomical phenomena are related to time periods. Which list is entirely correct? (Careful: some lists are partially correct.) A) Earth's rotation defines a day. The cycle of the Moon's phases takes about a month. Earth's orbit defines a year. Earth's cycle of axis precession takes 26,000 years. B) Earth's rotation defines a day. The cycle of the Moon's phases takes about a week. Earth's orbit defines a year. Earth's cycle of axis precession defines a month. C) Earth's rotation defines a day. The Sun's rotation defines a week. The Moon's rotation defines a month. Earth's orbit defines a year. D) Earth's rotation defines a day. The saros cycle of eclipses defines a month. Earth's orbit defines a year. Earth's cycle of axis precession takes 26,000 years. Answer: A 14) If we have a new Moon today, when we will have the next full Moon? A) in about 2 weeks B) in about 1 week C) in about a month D) in about 6 months Answer: A 18 Copyright © 2014 Pearson Education, Inc.

15) We cannot see a new moon in our sky because A) it is obscured by Earth's shadow. B) no sunlight is illuminating the Moon. C) a new moon is quite near the Sun in the sky. D) it is above the horizon during the daytime. Answer: C 16) The Moon always shows nearly the same face to Earth because A) the Moon does not rotate. B) sunlight always hits the same face of the Moon. C) the Moon rotates once in the same amount of time that it takes Earth to orbit the Sun once. D) the Moon rotates once in the same amount of time that it takes the Moon to orbit Earth once. Answer: D 17) Lunar eclipses can occur only during a A) new Moon. B) first quarter Moon. C) full Moon. D) third quarter Moon. Answer: C 18) What is the saros cycle? A) the 26,000-year cycle of the Earth's precession B) the roughly 18-year cycle over which the pattern of eclipses repeats C) the roughly one-month cycle of lunar phases in the sky D) the annual cycle of the seasons Answer: B 19) During the time that a planet is in its period of apparent retrograde motion, A) the planet moves backwards (clockwise as viewed from above Earth's north pole) in its orbit of the Sun. B) the planet appears to rise in the west and set in the east, rather than the usual rising in the east and setting in the west. C) over many days or weeks, the planet moves westward relative to the stars, rather than the usual eastward relative to the stars. D) the planet is getting closer to the Sun in its orbit. Answer: C 20) What is stellar parallax? A) It is the daily rise and set of the stars. B) It describes the fact that stars are actually moving relative to one another, even though to our eyes the stars appear fixed in the constellations. C) It is the slight back-and-forth shifting of star positions that occurs as we view the stars from different positions in Earth's orbit of the Sun. D) It is the change in the set of constellations that we see at different times of year in the evening sky. Answer: C 19 Copyright © 2014 Pearson Education, Inc.

2.5 Mastering Astronomy Concept Quiz 1) Which of the following statements about the celestial sphere is NOT true? A) The Earth is placed at the center of the celestial sphere. B) When we look in the sky, the stars all appear to be located on the celestial sphere. C) The "celestial sphere" is another name for our universe. D) The celestial sphere does not exist physically. Answer: C 2) The Andromeda Galaxy is faintly visible to the naked eye in the constellation Andromeda. Suppose instead it were located in the same direction in space as the center of the Milky Way Galaxy (but still at its current distance). How would it appear to the eye in that case? A) We could not see it at all. B) It would look about the same, but would be in the constellation Sagittarius instead of Andromeda. C) It would be much brighter, because it would be illuminated by the many stars in the center of our galaxy. D) It would look about the same, but it would be harder to pick out because its cloud-like appearance would make it blend in with the cloud-like appearance of the Milky Way in our sky. Answer: A 3) An angle of 1 arcsecond is A) about the width of your fist held at arm's length. B) about the width of a finger held at arm's length. C) less than the thickness of a human hair held at arm's length. D) slightly more than the width of a basketball held at arm's length. Answer: C 4) When traveling north from the United States into Canada, you'll see the North Star (Polaris) getting A) brighter. B) dimmer. C) higher in the sky. D) lower in the sky. Answer: C 5) Suppose you use the Southern Cross to determine that the south celestial pole appears 40 degrees above your horizon. Then you must be located at A) latitude 40 degrees north. B) latitude 50 degrees south. C) latitude 40 degrees south. D) longitude 40 degrees. Answer: C

6) Suppose you are facing north and you see the Big Dipper close to your northern horizon, with Polaris (and the Little Dipper) above it. Where will you see the Big Dipper in six hours? A) to the right of Polaris; that is, 90 degrees counterclockwise from its current position B) to the left of Polaris; that is, 90 degrees clockwise from its current position C) directly above Polaris D) still in the same place, below Polaris Answer: A 7) In any particular place on Earth, certain constellations are visible in the evening only at certain times of the year because A) our evening view of space depends on where Earth is located in its orbit around the Sun. B) during some times of year, some constellations drop below the southern horizon. C) some constellations are circumpolar. D) on any particular night, we can only see stars that are directly opposite (180 degrees away from) the Sun in the sky. Answer: A 8) The Sun's path, as viewed from the equator, is highest in the sky on A) the winter solstice. B) the spring and fall equinoxes. C) the summer solstice. D) the day when Earth is closest to the Sun. Answer: B 9) Suppose Earth's axis tilt was significantly greater than its current 23.5 degrees, but Earth's rotation period and orbital period were unchanged. Which statement below would not be true? A) Summers and winters would be more severe (for example, hotter and colder, respectively) than they are now. B) The region of Earth where the Sun does not rise on the winter solstice would be larger (extending farther south) than it is now. C) The length of each season (for example, the number of days from the summer solstice to the fall equinox) would be significantly longer than it is now. D) Polaris would not be our North star. Answer: C 10) If our year were twice as long (that is, if Earth took twice as many days to complete each orbit around the Sun), but Earth's rotation period and axis tilt were unchanged, then A) stars would take twice as long to rise and set. B) the cycle of precession would take 13,000 years instead of 26,000 years. C) the four seasons would each be twice as long as they are now. D) the Earth would not have seasons. Answer: C

11) How does Earth's varying distance from the Sun affect our seasons? A) It doesn't—Earth's orbital distance plays no significant role in the seasons. B) It makes summer warmer in the Northern Hemisphere than in the Southern Hemisphere. C) It is responsible for the fact that the seasons are opposite in the Northern and Southern hemispheres. D) It causes the seasons to be more extreme than they would be if the Earth's distance from the Sun were always the same. Answer: A 12) Suppose you live in the United States and you see a crescent Moon in your evening sky tonight. What will a friend in South America see tonight? A) Your friend will see a gibbous Moon. B) Your friend will also see a crescent Moon. C) Your friend will see a first quarter Moon. D) Your friend won't see the Moon tonight, because it is up only in the morning. Answer: B 13) Suppose it is full Moon. What phase of Earth would someone on the Moon see at this time? A) Full Earth B) New Earth C) First quarter Earth D) Earth does not go through phases as seen from the Moon. Answer: B 14) It's 6 A.M. and the Moon is at its highest point in your sky (crossing the meridian). What is the Moon's phase? A) new B) first quarter C) full D) third quarter Answer: D 15) You observe a full Moon rising at sunset. What will you see at midnight? A) a full Moon high in the sky B) a first quarter Moon C) a waning gibbous Moon D) a third quarter Moon Answer: A 16) All the following statements are true. Which one explains the reason that there is not a solar eclipse at every new Moon? A) The nodes of the Moon's orbit precess with an 18-year period. B) The orbital plane of the Moon is tilted slightly (by about 5 degrees) to the ecliptic plane. C) The Moon is only about 1/4 as large as Earth in diameter. D) The Moon goes through a complete cycle of phases about every 29 1/2 days. Answer: B 22 Copyright © 2014 Pearson Education, Inc.

17) For most of history, the lack of observable stellar parallax was interpreted to mean that A) stars must all lie at the same distance from Earth, on the celestial sphere. B) stars were too far away for parallax to be measured with available technology. C) Earth is stationary at the center of the universe. D) Galileo's theories of the universe were essentially correct. Answer: C 18) During the period each year when we see Mars undergoing apparent retrograde motion in our sky, what is really going on in space? A) Mars is moving around the Sun in the opposite direction from which Earth is moving around the Sun. B) Earth and Mars are getting closer together. C) Earth is catching up with and passing by Mars in their respective orbits. D) Earth and Mars are on opposite sides of the Sun. Answer: C 19) Suppose you see a photo showing Jupiter half in sunlight and half in shadow (that is, a first quarter Jupiter). This photo might have been taken by A) the Galileo spacecraft that orbited Jupiter in the 1990s. B) the Hubble Space Telescope (which orbits Earth). C) the Keck Telescope on Mauna Kea, Hawaii. D) the Arecibo Radio Telescope in Puerto Rico. Answer: A

The Cosmic Perspective, 7e (Bennett et al.) Chapter 3 The Science of Astronomy 3.1 Multiple-Choice Questions 1) People of central Africa predicted the weather by A) recording the seasonal changes in average temperature. B) observing the path of the planets across the sky. C) observing the length of the lunar cycle. D) observing the orientation of the crescent Moon relative to the horizon. E) observing the location of the Moon relative to the Sun in the sky. Answer: D 2) The names of the seven days of the week are based on the A) seven naked-eye objects that appear to move among the constellations. B) seven planets closest to the Sun. C) seven brightest stars in the prominent constellation Orion. D) most popular Norse gods. E) seven largest constellations of the ancient world. Answer: A 3) Suppose the planet Uranus were much brighter in the sky, so that it was as easily visible to the naked eye as Jupiter or Saturn. Which one of the following statements would most likely be true in that case? A) Its brightness would make it possible to read by starlight at night. B) Its gravity would cause the tides to be much higher than they actually are. C) Its slow motion through the sky would have led it to be named after the Goddess of Procrastination. D) The discovery that Earth is a planet going around the Sun would have come hundreds of years earlier. E) A week would have eight days instead of seven. Answer: E 4) Compared with the standard hour of 60 minutes used today, the hour of ancient Egypt A) was longer than the hour used today. B) was shorter than the hour used today. C) differed in length depending on the pharaoh in power at the time. D) was longer than 60 minutes in the summer and shorter than 60 minutes in the winter. E) divided the entire day into 12 equal parts. Answer: D

5) In order to tell time at night, the ancient Egyptians of 3000 B.C. used A) sundials, with light provided by the Moon. B) water clocks, measuring the flow of water through an opening. C) hourglasses, measuring the flow of sand through an opening. D) Moon clocks, which measured time based on the Moon's position relative to the stars. E) star clocks, which measured time based on the positions of stars at particular times of night and particular times of year. Answer: E 6) Historians trace the origins of a 24-hour day to A) the druids of Stonehenge. B) the ancient Egyptians. C) the Mayans. D) the Aztecs. E) the Babylonian astronomer, Meton. Answer: B 7) What do the structures of Stonehenge, the Templo Mayor, and the Sun Dagger all have in common? A) They were all places used for religious sacrifice. B) They were all built on the orders of ancient Mediterranean kings. C) They all can be used as lunar calendars. D) They were all used by ancient peoples for astronomical observations. E) all of the above Answer: D 8) At the Sun Dagger in New Mexico, a dagger-shaped beam of sunlight pierces a spiral A) every day at noon. B) at noon on the summer solstice. C) at sunset on the spring equinox. D) at noon on the day of full Moon each month. E) during the totality of a total solar eclipse. Answer: B 9) The Muslim fast of Ramadan occurs A) on the summer solstice. B) during the ninth month of a 12-month lunar cycle. C) on the spring equinox. D) during a thirteenth month of the Metonic cycle. E) at the end of the Metonic cycle. Answer: B

10) The Metonic cycle is the A) 29 1/2-day period of the lunar cycle. B) 12-month period of a lunar calendar. C) 19-year period over which the lunar phases occur on about the same dates. D) 18-year, 11-day period over which the pattern of eclipses repeats. E) period between successive Easters. Answer: C 11) The Jewish calendar is kept roughly synchronized with a solar calendar by A) adding a thirteenth lunar month to 7 out of every 19 years. B) having a thirteenth month with 5 days each year. C) skipping a month every 7 out of 19 years. D) having the first lunar month begin on the spring equinox. E) having the first lunar month begin on the summer solstice. Answer: A 12) Which ancient culture had the greatest known success in predicting eclipses? A) Aztecs B) Mayans C) Egyptians D) Babylonians E) Greeks Answer: B 13) The path that led to modern science emerged from ancient civilizations in which part of the world? A) Central and South America B) the Mediterranean and the Middle East C) North America D) China E) Southern Asia Answer: B 14) When and where did the Library of Alexandria exist? A) from A.D. 600 to A.D. 1800 in Greece B) from A.D. 600 to A.D. 1800 in Egypt C) from 300 B.C. to A.D. 400 in Rome D) from 300 B.C. to A.D. 400 in Greece E) from 300 B.C. to A.D. 400 in Egypt Answer: E

15) How did Eratosthenes estimate the size of Earth in 240 B.C.? A) by observing the duration of a solar eclipse B) by measuring the size of Earth's shadow on the Moon in a lunar eclipse C) by comparing the maximum altitude of the Sun in two cities at different latitudes D) by sending fleets of ships around Earth E) We don't know how he did it since all his writings were destroyed. Answer: C 16) Which of the following statements about scientific models is true? A) A model tries to represent all aspects of nature. B) A model tries to represent only one aspect of nature. C) A model can be used to explain and predict real phenomena. D) All models that explain nature well are correct. E) All current models are correct. Answer: C 17) Ptolemy was important in the history of astronomy because he A) developed a model of the solar system that made sufficiently accurate predictions of planetary positions to remain in use for many centuries. B) developed a scientifically accurate model of the universe. C) was the first to believe in an Earth-centered universe. D) was the first to create a model of the solar system that placed the Sun rather than Earth at the center. E) was the first to believe that all orbits are perfect circles. Answer: A 18) When did Ptolemy live? A) about 5000 years ago B) about 2000 years ago C) about 1000 years ago D) about 500 years ago E) about 100 years ago Answer: B 19) How did the Ptolemaic model explain the apparent retrograde motion of the planets? A) It held that sometimes the planets moved backward along their circular orbits. B) It placed the Sun at the center so that the planets' apparent retrograde motion was seen as Earth passed each one in its orbit. C) It varied the motion of the celestial sphere so that it sometimes moved backward. D) It held that the planets moved along small circles that moved on larger circles around the Sun. E) It held that the planets moved along small circles that moved on larger circles around Earth. Answer: E

20) Why did Ptolemy have the planets orbiting Earth on "circles upon circles" in his model of the universe? A) to explain why more distant planets take longer to make a circuit through the constellations of the zodiac B) to explain the fact that planets sometimes appear to move westward, rather than eastward, relative to the stars in our sky C) to explain why the Greeks were unable to detect stellar parallax D) to properly account for the varying distances of the planets from Earth E) to explain why Venus goes through phases as seen from Earth Answer: B 21) Where was the Sun in Ptolemy's model of the universe? A) at the center B) slightly offset from the center C) between Earth and the Moon's orbit D) between the orbits of Venus and Mars E) at the outer edge, beyond Saturn's orbit Answer: D 22) During the Dark Ages in Europe, the scientific work of the ancient Greeks was preserved and further developed primarily by scholars in A) Baghdad. B) Greece. C) Rome. D) India. E) China. Answer: A 23) The controversial book of this famous person, published in 1543 (the year of his death), suggested that Earth and other planets orbit the Sun. A) Tycho Brahe B) Copernicus C) Kepler D) Galileo E) Ptolemy Answer: B 24) He developed a system for predicting planetary positions that remained in use for some 1,500 years. A) Tycho Brahe B) Copernicus C) Kepler D) Galileo E) Ptolemy Answer: E

25) He was the first to prove that comets lie beyond Earth's atmosphere. A) Tycho Brahe B) Copernicus C) Kepler D) Galileo E) Aristotle Answer: A 26) He discovered that the orbits of planets are ellipses. A) Tycho Brahe B) Copernicus C) Kepler D) Galileo E) Ptolemy Answer: C 27) He discovered that Jupiter has moons. A) Tycho Brahe B) Aristotle C) Kepler D) Galileo E) Ptolemy Answer: D 28) He discovered what we now call Newton's first law of motion. A) Tycho Brahe B) Copernicus C) Kepler D) Galileo E) Ptolemy Answer: D 29) When Copernicus first created his Sun-centered model of the universe, it did not lead to substantially better predictions of planetary positions than the Ptolemaic model. Why not? A) Copernicus misjudged the distances between the planets. B) Copernicus misjudged the speeds at which the planets orbit the Sun. C) Copernicus placed the planets in the wrong order going outward from the Sun. D) Copernicus placed the Sun at the center but did not realize that the Moon orbits Earth. E) Copernicus used perfect circles for the orbits of the planets. Answer: E

30) When did Copernicus live? A) about 5000 years ago B) about 2000 years ago C) about 1000 years ago D) about 500 years ago E) about 100 years ago Answer: D 31) Which of the following was not observed by Galileo? A) craters on the Moon B) stellar parallax C) sunspots D) Jupiter's moons E) phases of Venus Answer: B 32) One of the "nails in the coffin" for Earth-centered universe was A) the retrograde motion of the planets. B) the phases of the Moon. C) eclipses of the Sun. D) Galileo's observation of stars in the Milky Way. E) Galileo's observations of the moons of Jupiter. Answer: E 33) When we see Venus in its full phase, what phase would Earth be in as seen by a hypothetical Venetian? A) full B) new C) first quarter D) third quarter E) waning crescent Answer: A 34) Which of the following is not one of, nor follows directly from, Kepler's laws? A) The orbit of each planet about the Sun is an ellipse with the Sun at one focus. B) As a planet moves around its orbit, it sweeps out equal areas in equal times. C) The force of attraction between any two objects decreases with the square of the distance between their centers. D) A planet travels faster when it is nearer to the Sun and slower when it is farther from the Sun. E) More distant planets move at slower speeds. Answer: C

35) Kepler's third law, p2 = a3, means that A) a planet's period does not depend on the eccentricity of its orbit. B) all orbits with the same semimajor axis have the same period. C) the period of a planet does not depend on its mass. D) planets that are farther from the Sun move at slower average speeds than nearer planets. E) All of the above are correct. Answer: E 36) From Kepler's third law, a hypothetical planet that is twice as far from the Sun as Earth should have a period of A) 1/2 Earth year. B) 1 Earth year. C) 2 Earth years. D) more than 2 Earth years. E) It depends on the planet's mass. Answer: D 37) From Kepler's third law, an asteroid with an orbital period of 8 years lies at an average distance from the Sun equal to A) 2 astronomical units. B) 4 astronomical units. C) 8 astronomical units. D) 16 astronomical units. E) It depends on the asteroid's mass. Answer: B 38) Kepler's second law, which states that as a planet moves around its orbit it sweeps out equal areas in equal times, means that A) a planet travels faster when it is nearer to the Sun and slower when it is farther from the Sun. B) a planet's period does not depend on the eccentricity of its orbit. C) planets that are farther from the Sun move at slower average speeds than nearer planets. D) the period of a planet does not depend on its mass. E) planets have circular orbits. Answer: A 39) All the following statements are true. Which one follows directly from Kepler's third law? A) Venus is more massive than Mercury. B) Venus orbits the Sun at a slower average speed than Mercury. C) Venus is larger than Mercury. D) Venus has a thicker atmosphere than Mercury. Answer: B

40) What do scientists mean by verifiable observations? A) statements that a person can, in principle, verify for himself or herself B) statements that anyone would agree are obvious C) observations that can be interpreted in only one way D) observations that a model does not have to predict E) observations that support a scientific theory Answer: A 41) What is meant by a scientific paradigm? A) a conundrum or unexplained set of facts B) a radical change in scientific thought C) a generally well-established scientific theory or set of theories D) a pseudoscientific idea E) a historical theory that has been proved inaccurate Answer: C 42) What is meant by a hypothesis? A) a natural phenomenon that requires explanation B) an explanation for a phenomenon that makes a prediction C) a tentative understanding of a natural phenomenon D) a pseudoscientific idea E) a historical theory that has been proved inaccurate Answer: B 43) What is meant by Occam's Razor? A) a well-designed experiment that clearly shows the differences between two competing theories B) a poorly designed experiment that fails to show the difference between two competing theories C) the idea that scientists should prefer the simpler of two models that agree equally well with observations D) the fine line between science and pseudoscience E) the shaving implement of a medieval scholar Answer: C 44) Which of the following statements about scientific theories is not true? A) A theory cannot be taken seriously by scientists if it contradicts other theories developed by scientists over the past several hundred years. B) A theory is a model designed to explain a number of observed facts. C) If even a single new fact is discovered that contradicts what we expect according to a particular theory, then the theory must be revised or discarded. D) A theory must make predictions that can be checked by observation or experiment. E) A theory can never be proved beyond all doubt; we can only hope to collect more and more evidence that might support it. Answer: A

45) The ancient goal of astrology was to A) understand the origin of Earth. B) make a more accurate model of the universe. C) predict the passing of the seasons. D) predict human events. E) antagonize astronomers. Answer: D 46) The astrology practiced by those who cast predictive horoscopes can be tested by A) asking astrologers if it works. B) asking astronomers if it works. C) counting how many times the predictions come true. D) comparing how often the predictions come true to what would be expected by pure chance. E) polling people to find out what percentage believe their horoscopes to be accurate. Answer: D 47) Which of the following best explains the success of the central African rainfall-prediction technique of observing the waxing crescent Moon? A) When the Moon is aligned in a U-shape, it can hold more water, so there is more rain. When it is tilted, it can hold less, so the weather is drier. B) When the Moon is in Capricorn, there is always more tempestuous weather, while when in Pisces, it is just plain rainy. C) Clouds cover part of the Moon's surface, so the smaller the crescent, the more likely it is to rain. D) The Moon's orientation varies seasonally, and so does the weather. E) The Moon causes the tides and affects the weather. Answer: D Process of Science: Assume we have data indicating a strong positive correlation between acupuncture treatments and recovery of patients from, say, cocaine addiction. However, let's also assume that every hypothesis we have for a mechanism of action (i.e., how acupuncture could work to help cure addiction) can be shown to be false. The patients, however, all claim to know that the acupuncture is what cured them. Which of the following conclusions are supported by our data? 48) Could acupuncture be responsible for the patients' recovery? A) No. If there is no plausible mechanism of action, then clearly acupuncture cannot be responsible for their healing. B) Yes. Just because we don't understand the mechanism doesn't mean the process does not occur. C) No. Acupuncture is not accepted by most medical doctors, therefore it isn't effective. D) Yes. If the patients got better, then the acupuncture must be effective. Answer: B

49) Must acupuncture be responsible for the patients' recovery? A) No. Acupuncture may be responsible for the healing, or it may not. Correlation does not necessarily imply causation. B) Yes. If the study was run by qualified M.D.s, then we should respect their findings that acupuncture cured these patients. C) No. Acupuncture is hippie, new age stuff, and is not respected by reputable doctors. D) Yes. The patients stated afterwards that they knew it had helped, and these people know their own bodies better than we do. Answer: A 50) Process of Science: What is Occam's razor? A) The idea that scientists should prefer the simpler of two models that agree equally well with observations. B) The principle that everyone should agree on a theory before it is considered correct. C) A long, steep cliff on Mercury that may have been produced as the planet contracted as it formed. D) The principal that any theory can be verified by others. E) An unusual implement that Professor Occam uses to remove facial hair. Answer: A 3.2 True/False Questions 1) The names of the seven days of the week are derived from the names of the members of the solar system that are visible to the naked eye. Answer: TRUE 2) The Polynesian navigators of the South Pacific found their way primarily by observing the position of Polaris in the night sky. Answer: FALSE 3) The Ptolemaic model of the solar system was useless for predicting planetary positions. Answer: FALSE 4) Copernicus was the first person to suggest a Sun-centered solar system. Answer: FALSE 5) Copernicus's model of the solar system gave much better predictions than the model of Ptolemy. Answer: FALSE 6) In the Ptolemaic system, Venus should not show phases. Answer: FALSE 7) Galileo found "imperfections" on the Sun in the form of sunspots and "imperfections" on the Moon in the form of mountains and valleys. Answer: TRUE 11 Copyright © 2014 Pearson Education, Inc.

8) It is possible for science as a whole to be objective despite the fact that all individual scientists have personal biases and beliefs. Answer: TRUE 9) Scientific thinking developed only in the past few decades. Answer: FALSE 10) Scientific theories can never be proved true beyond all doubt. Answer: TRUE 11) A scientific model must make a testable prediction. Answer: TRUE 12) Astronomy and astrology were often practiced together in ancient cultures, and astrology played an important role in the historical development of astronomy. Answer: TRUE 13) Nonscientific practices that make no claims about how the natural world works do not conflict with science. Answer: TRUE 14) Process of Science: I am doing science when I already know the answer to my scientific question and I am searching for evidence in the natural world strictly to support what I know. Answer: FALSE 15) Process of Science: If any single test of a scientific hypothesis contradicts it, the hypothesis must be revised. (Assume that you've ruled out errors in the testing process; that is, the test result really does contradict the hypothesis.) Answer: TRUE 3.3 Short Answer Questions 1) How did ancient peoples of central Africa predict the weather? Answer: They observed the orientation of the crescent Moon relative to the horizon. The orientation of the "horns" is related to rainfall patterns. 2) What is special about the lines in the Nazca Desert of Peru? Answer: There are more than 800 lines etched in the Nazca Desert of Peru. Some lines are aligned to places where bright stars rose at that time, or where the Sun rose at particular times of the year. There are also many figures of animals. The figures are so large that it is easiest to see the patterns from the air. 3) Why was a knowledge of the stars so important to Polynesians? Answer: The Polynesian people live on a group of widely separated islands in the South Pacific. Knowledge of the stars allowed navigators to determine their latitude and direction, both essential for traveling the large distances from island to island. 12 Copyright © 2014 Pearson Education, Inc.

4) Describe how Eratosthenes first measured the size of Earth over 2,000 years ago. Answer: Eratosthenes used measurements of the angle of the Sun in the sky at noon on the summer solstice in two places in Egypt. It was directly overhead in Syene and cast no shadows. In Alexandria, however, there was a slight shadow, indicating that the Sun was 7 degrees away from overhead. Eratosthenes concluded that Alexandria lies at a latitude 7 degrees north of Syene. The circumference of Earth is then the distance between Syene and Alexandria divided by the fraction of the circle (7/360) that the two cities span. 5) Describe the Ptolemaic model of the solar system. How did Ptolemy account for the apparent retrograde motion of the planets? Answer: Although Ptolemy's model was an Earth-centered model of the solar system, it was sufficiently accurate to remain in use for 1,500 years. His model used the ancient idea that all motions in the heavens must be perfect circles. Therefore, the planets moved on circles that orbited on larger circles around Earth. This "circle upon circle" motion accounted for the apparent retrograde motion of the planets. Ptolemy carefully selected sizes for the circles to reproduce the motions seen in the sky. He also placed Earth slightly off-center to improve model predictions even more. 6) Describe one major accomplishment for each of the following people: Copernicus, Tycho Brahe, Kepler, Galileo, Newton. Answer: Many possible answers: e.g., Copernicus: Sun-centered system; Tycho Brahe: collected key data for Kepler's discoveries; Kepler: laws of planetary motion; Galileo: overturning Aristotelian physics; Newton: laws of motion and gravity. 7) State Kepler's three laws of planetary motion. Answer: 1. The orbit of each planet is an ellipse with the Sun at one focus. 2. As a planet moves around its orbit, it sweeps out equal areas in equal times. 3. A planet's period squared is equal to its semimajor axis cubed. 8) Summarize in your own words, the three "hallmarks" of science? Answer: See Figure 3.26. As an example: 1. The quest to explain an observation by building on our knowledge of other aspects of nature 2. The creation and testing of models that explain observations as simply as possible 3. Models make testable predictions and are modified or abandoned if the predictions do not agree with observations 9) What is pseudoscience? Answer: Pseudoscience is the explanation of events through models that purport to be scientific but which, in practice, do not contain the hallmarks of science. For example, predictions may be made but models are not adjusted if the predictions fail to match the observations.

10) Describe what a scientific test of astrology would involve. Answer: First of all, science can only test the types of astrology that claim to be able to make predictions about future events or about characteristics of a person's personality and life. A scientific test of astrology requires evaluating many horoscopes and comparing their accuracy to what would be expected by pure chance. Therefore, one would have to evaluate how often a predicted event would likely occur naturally. Only if the astrologer could substantially beat the odds of predicting this event could one safely say that the astrologer could predict the future, at least concerning this particular event. 11) Process of Science: Give a scientific explanation of the success of the central African rainfall-prediction technique of observing the waxing crescent Moon. Can the Moon cause a change in rainfall? Or vice versa? Answer: The Moon's orientation varies seasonally, and so does the weather, so the orientation and the weather are correlated, but one does not cause the other. 12) Process of Science: Why is it not science to start with the answer to a question and look for evidence to support it? Answer: The process of science involves asking a question and then forming testable hypotheses in order to gather evidence either to support or to refute it. So-called "cherry picking" of evidence to support an idea and ignoring evidence that may refute it does not advance knowledge and is not the scientific method. 3.4 Mastering Astronomy Reading Quiz 1) What practical value did astronomy offer to ancient civilizations? A) It helped them keep track of time and seasons, and it was used by some cultures for navigation. B) It allowed them to predict eclipses with great accuracy. C) It helped them understand our cosmic origins. D) It helped them find uses for ancient structures like Stonehenge. Answer: A 2) Scientific thinking is A) based on everyday ideas of observation and trial-and-error experiments. B) completely different from any other type of thinking. C) a difficult process that only a handful of people can do well. D) an ancient mode of thinking first invented in Egypt. Answer: A 3) The names of the seven days of the week are based on A) the names of the seven planets closest to the Sun. B) the seven most prominent constellations in the summer sky. C) the names of prophets in the Bible. D) the seven naked-eye objects that appear to move among the constellations. Answer: D

4) The Metonic cycle is A) used to keep lunar calendars approximately synchronized with solar calendars. B) used to predict the future orientation of the Earth's axis in space. C) the ancient Greek name for the cycle of lunar phases that repeats every 29 1/2 days. D) the 18-year, 11-day period over which the pattern of eclipses repeats. Answer: A 5) Ptolemy was important in the history of astronomy because he A) eloped a model of the solar system that made sufficiently accurate predictions of planetary positions to remain in use for many centuries. B) developed the first scientific model of the universe. C) was the first to create a model of the solar system that placed the Sun rather than the Earth at the center. D) was the first to believe that all orbits are perfect circles. Answer: A 6) The ancient Greeks get a lot of attention for their contributions to science because A) they were the first people known to try to explain nature with models based on reason and mathematics, without resort to the supernatural. B) the books of every other culture were lost in the destruction of the library of Alexandria. C) they were the first people to realize that Earth is a planet orbiting the Sun. D) they were the only ancient culture that kept written records of their astronomical observations. Answer: A 7) What do we mean by a geocentric model of the universe? A) It is a model designed to explain what we see in the sky while having the Earth located in the center of the universe. B) It is a model designed to explain what we see in the sky while having the Earth orbit the Sun. C) It is the name given to sphere-shaped models that show all the constellations as they appear in our sky on the celestial sphere. D) It is a model of the Milky Way Galaxy that has our solar system located at its center. Answer: A 8) What was the Ptolemaic model? A) an Earth-centered model of planetary motion published by Ptolemy B) the Earth-centered model of the cosmos in which the Earth was surrounded by seven perfect spheres, one each for the Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn C) the first scientific model to successfully predict solar and lunar eclipses D) a Sun-centered model of planetary motion published by Ptolemy Answer: A

9) The great contribution of Nicholas Copernicus was to A) create a detailed model of our solar system with the Sun rather than Earth at the center. B) prove that the Earth is not the center of the universe. C) discover the laws of planetary motion. D) discover the law of gravity. Answer: A 10) The great contribution of Tycho Brahe was to A) observe planetary positions with sufficient accuracy so that Kepler could later use the data to discover the laws of planetary motion. B) discover four moons orbiting Jupiter, thereby lending strong support to the idea that the Earth is not the center of the universe. C) offer the first detailed model of a Sun-centered solar system, thereby beginning the process of overturning the Earth-centered model of the Greeks. D) discover that planets orbit the Sun in elliptical orbits with varying speed. Answer: A 11) Which of the following was not observed by Galileo? A) stellar parallax B) mountains and valleys on the Moon C) four moons orbiting Jupiter D) phases of Venus Answer: A 12) Which of the following statements about an ellipse is not true? A) The focus of an ellipse is always located precisely at the center of the ellipse. B) A circle is considered to be a special type of ellipse. C) The semimajor axis of an ellipse is half the length of the longest line that you can draw across an ellipse. D) An ellipse with a large eccentricity looks much more elongated (stretched out) than an ellipse with a small eccentricity. Answer: A 13) Which of the following is not one of, nor a direct consequence of, Kepler's Laws? A) The force of attraction between any two objects decreases with the square of the distance between their centers. B) As a planet moves around its orbit, it sweeps out equal areas in equal times. C) The orbit of each planet about the Sun is an ellipse with the Sun at one focus. D) More distant planets orbit the Sun at slower speeds. E) A planet or comet in a noncircular orbit travels faster when it is nearer to the Sun and slower when it is farther from the Sun. Answer: A

14) Scientific models are used to A) present the scale of the solar system to the general public. B) make specific predictions that can be tested through observations or experiments. C) make miniature representations of the universe. D) prove that past paradigms no longer hold true. Answer: B 15) In science, a broad idea that has been repeatedly verified so as to give scientists great confidence that it represents reality is called A) a paradigm. B) a hypothesis. C) Ptolemaic model. D) a theory. Answer: D 16) Which of the following best describes how modern astronomers view astrology? A) Astrology played an important part in the development of astronomy in ancient times, but it is not a science by modern standards. B) Astrology is a synonym for astronomy. C) Astrology was a great idea until it was disprove by the work of Copernicus, Tycho, Kepler, and Galileo. D) Astrology is new age mumbo-jumbo that was a waste of time when it was invented thousands of years ago and remains a waste of time today. Answer: A 3.5 Mastering Astronomy Concept Quiz 1) Suppose the planet Uranus were much brighter in the sky, so that it was as easily visible to the naked eye as Jupiter or Saturn. Which one of the following statements would most likely be true in that case? A) A week would have eight days instead of seven. B) Its brightness would make it possible to read by starlight at night. C) Its gravity would cause the tides to be much higher than they actually are. D) The discovery that the Earth is a planet going around the Sun would have come hundreds of years earlier. E) Its slow motion through the sky would have led it to be named after the Goddess of Procrastination. Answer: A 2) How does a 12-month lunar calendar differ from our 12-month solar calendar? A) It has about 11 fewer days. B) It does not have seasons. C) Its new year always occurs in February instead of on January 1. D) It uses a 23-hour rather than a 24-hour day. Answer: A

3) Which of the following best describes a set of conditions under which archaeoastronomers would conclude that an ancient structure was used for astronomical purposes? A) The structure has holes in the ceiling that allow viewing the passage of constellations that figure prominently in the culture's folklore, and many other structures built by the same culture have ceiling holes placed in the same way. B) They find that, looking out from the center of the building, there are two windows that align with the rise and set points of two bright stars. C) The structure has 29 straight lines pointing out from a center, just like there are 29 days in the lunar cycle. D) The structure has the same dome shape as modern astronomical observatories. Answer: A 4) How did the Ptolemaic model explain the apparent retrograde motion of the planets? A) The planets moved along small circles that moved on larger circles around Earth. B) The planets sometimes stopped moving and then reversed to move backward along their circular orbits. C) The model showed that apparent retrograde motion occurs as Earth passes by another planet in its orbit of the Sun. D) The planets resided on giant spheres that sometimes turned clockwise and sometimes turned counterclockwise. Answer: A 5) When Copernicus first created his Sun-centered model of the universe, it did not lead to substantially better predictions of planetary positions than the Ptolemaic model. Why not? A) Copernicus used perfect circles for the orbits of the planets. B) Copernicus placed the planets in the wrong order going outward from the Sun. C) Copernicus misjudged the distances between the planets. D) Copernicus placed the Sun at the center, but did not realize that the Moon orbits Earth. Answer: A 6) Earth is farthest from the Sun in July and closest to the Sun in January. During which Northern Hemisphere season is Earth moving fastest in its orbit? A) Spring B) Summer C) Fall D) Winter Answer: D 7) According to Kepler's third law (p2 = a3), how does a planet's mass affect its orbit around the Sun? A) A planet's mass has no effect on its orbit around the Sun. B) More massive planets orbit the Sun at higher average speed. C) More massive planets must have more circular orbits. D) A more massive planet must have a larger semimajor axis. Answer: A

8) All the following statements are true. Which one follows directly from Kepler's third law (p2 = a3)? A) Venus orbits the Sun at a slower average speed than Mercury. B) Venus is more massive than Mercury. C) Venus takes longer to rotate than it does to orbit the Sun. D) Venus has a thicker atmosphere than Mercury. Answer: A 9) Suppose a comet orbits the Sun on a highly eccentric orbit with an average (semimajor axis) distance of 1 AU. How long does it take to complete each orbit, and how do we know? A) One year, which we know from Kepler's third law. B) It depends on the eccentricity of the orbit, as described by Kepler's second law. C) It depends on the eccentricity of the orbit, as described by Kepler's first law. D) Each orbit should take about 2 years, because the eccentricity is so large. Answer: A 10) Galileo challenged the idea that objects in the heavens were perfect by A) showing that heavy objects fall at the same rate as lighter objects. B) observing sunspots on the Sun and mountains on the Moon. C) proving Kepler's laws were correct. D) inventing the telescope. Answer: B 11) Galileo observed all of the following. Which observation offered direct proof of a planet orbiting the Sun? A) phases of Venus B) four moons of Jupiter C) patterns of shadow and sunlight near the dividing line between the light and dark portions of the Moon's face D) The Milky Way is composed of many individual stars. Answer: A 12) Which of the following is not consistent with the major hallmarks of science? A) Science consists of proven theories that are understood to be true explanations of reality. B) Scientific explanations should be based solely on natural causes. C) Science progresses through the creation and testing of models that explain observation as simply as possible. D) A scientific model must make testable predictions. Answer: A

13) Which of the following is not part of a good scientific theory? A) A scientific theory cannot be accepted until it has been proven true beyond all doubt. B) A scientific theory must make testable predictions that, if found to be incorrect, could lead to its own modification or demise. C) A scientific theory must explain a wide variety of phenomena observed in the natural world. D) A scientific theory should be based on natural processes and should not invoke the supernatural or divine. Answer: A 14) Only one of the statements below uses the term theory in its correct, scientific sense. Which one? A) Einstein's theory of relativity has been tested and verified thousands of times. B) Evolution is only a theory, so there's no reason to think it really happened. C) I have a new theory about the cause of earthquakes, and I plan to start testing it soon. D) I wrote a theory that is 152 pages long. Answer: A 15) The astrology practiced by those who cast predictive horoscopes can be tested by A) comparing how often the predictions come true to what would be expected by pure chance. B) asking astrologers if it works. C) polling people to find out what percentage believe their horoscopes to be accurate. D) counting how many times the predictions come true. Answer: A 16) Imagine for a moment that despite all the evidence, Earth actually is not rotating and orbiting the Sun. Which of these hypothetical observations (none of them are real) would be inconsistent with our Sun-centered view of the solar system? A) We discover a small planet beyond Saturn that rises in the west and sets in the east each day. B) We discover an Earth-sized planet orbiting the Sun beyond the orbit of Pluto. C) We find that we are unable to measure any parallax for a distant galaxy. D) We discover that the universe is actually contracting, not expanding. Answer: A

The Cosmic Perspective, 7e (Bennett et al.) Chapter 4 Making Sense of the Universe: Understanding Motion, Energy, and Gravity 4.1 Multiple-Choice Questions 1) Which of the following is an example in which you are traveling at constant speed but not at constant velocity? A) rolling freely down a hill in a cart, traveling in a straight line B) driving backward at exactly 50 km/hr C) driving around in a circle at exactly 100 km/hr D) jumping up and down, with a period of exactly 60 hops per minute E) none of the above Answer: C 2) What is the acceleration of gravity of Earth? A) 9.8 m/s2 downward B) 9.8 m/s downward C) 9.8 km/s2 downward D) 9.8 m2/s downward E) 9.8 km/s downward Answer: A 3) If you drop a rock from a great height, about how fast will it be falling after 5 seconds, neglecting air resistance? A) It depends on how heavy it is. B) It depends on what shape it is. C) 10 m/s D) 15 m/s E) 50 m/s Answer: E 4) Momentum is defined as A) mass times speed. B) mass times velocity. C) force times velocity. D) mass times acceleration. E) force times acceleration. Answer: B 5) If an object's velocity is doubled, its momentum is A) halved. B) unchanged. C) doubled. D) quadrupled. E) dependent on its acceleration. Answer: C 1 Copyright © 2014 Pearson Education, Inc.

6) As long as an object is not gaining or losing mass, a net force on the object will cause a change in A) acceleration. B) direction. C) weight. D) speed. E) velocity. Answer: E 7) If your mass is 60 kg on Earth, what would your mass be on the Moon? A) 10 lb B) 10 kg C) 50 kg D) 60 kg E) 60 lb Answer: D 8) In which of the following cases would you feel weightless? A) while walking on the Moon B) while falling from an airplane with your parachute open C) while traveling through space in an accelerating rocket D) while falling from a roof E) none of the above Answer: D 9) You are standing on a scale in an elevator. Suddenly you notice your weight decreases. What do you conclude? A) The elevator is accelerating upwards. B) The elevator is moving at a constant velocity upwards. C) The elevator is accelerating downwards. D) The elevator is moving at a constant velocity downwards. E) Your diet is working. Answer: C 10) What would happen if the Space Shuttle were launched with a speed greater than Earth's escape velocity? A) It would travel away from Earth into the solar system. B) It would travel in a higher orbit around Earth. C) It would take less time to reach its bound orbit. D) It would orbit Earth at a faster velocity. E) It would be in an unstable orbit. Answer: A

11) Suppose an object is moving in a straight line at 50 miles/hr. According to Newton's first law of motion, the object will A) continue to move in the same way forever, no matter what happens. B) continue to move in the same way until it is acted upon by a force. C) eventually slow down and come to a stop. D) continue to move in a straight line forever if it is in space, but slow and stop otherwise. E) continually slow down but never quite come to a complete stop. Answer: B 12) Which of the following statements is not one of Newton's laws of motion? A) What goes up must come down. B) The rate of change of momentum of an object is equal to the net force applied to the object. C) In the absence of a net force, an object moves with constant velocity. D) For any force, there always is an equal and opposite reaction force. E) All of the above are Newton's laws of motion. Answer: A 13) Newton's second law of motion tells us that the net force applied to an object equals its A) mass times energy. B) momentum times velocity. C) mass times velocity. D) energy times acceleration. E) mass times acceleration. Answer: E 14) How does the Space Shuttle take off? A) Its rocket engines push against the launch pad propelling the shuttle upwards. B) It converts mass-energy to kinetic energy. C) It achieves lift from its wings in the same way that airplanes do. D) Hot gas shoots out from the rocket and, by conservation of momentum, the shuttle moves in the opposite direction. E) The hot rocket exhaust expands the air beneath the shuttle, propelling it forward. Answer: D 15) The movement of a pool ball, after being struck by a cue, is an example of A) Newton's first law of motion. B) Newton's second law of motion. C) Newton's third law of motion. D) the universal law of gravitation. E) conservation of momentum. Answer: B

16) The fact that the Voyager spacecraft continue to speed out of the solar system, even though its rockets have no fuel, is an example of A) Newton's first law of motion. B) Newton's second law of motion. C) Newton's third law of motion. D) the universal law of gravitation. E) none of the above. Answer: A 17) Changing the orbit of a spacecraft by firing thrusters is an example of A) Newton's first law of motion. B) Newton's second law of motion. C) Newton's third law of motion. D) the universal law of gravitation. E) none of the above. Answer: C 18) What quantities does angular momentum depend upon? A) mass and velocity B) mass, velocity, and radius C) force and radius D) force, velocity, and radius E) momentum and angular velocity Answer: B 19) A skater can spin faster by pulling her arms closer to her body or spin slower by spreading her arms out from her body. This is due to A) the law of gravity. B) Newton's third law. C) conservation of momentum. D) conservation of angular momentum. E) conservation of energy. Answer: D 20) Which of the following is not a conserved quantity? A) energy B) momentum C) angular momentum D) radiation Answer: D

21) Which of the following is not a unit of energy? A) Calorie B) joule C) calorie D) kilowatt E) British thermal unit Answer: D 22) Radiative energy is A) heat energy. B) energy from nuclear power plants. C) energy carried by light. D) energy used to power home radiators. E) energy of motion. Answer: C 23) Gasoline is useful in cars because it has A) gravitational potential energy. B) chemical potential energy. C) electrical potential energy. D) kinetic energy. E) radiative energy. Answer: B 24) Which of the following is a form of electrical potential energy? A) coal B) energy coming to your house from power companies C) energy from the Sun D) light from a fluorescent bulb E) moving blades on an electric mixer Answer: B 25) Which object has the most kinetic energy? A) a 4-ton truck moving 50 km/hr B) a 3-ton truck moving 70 km/hr C) a 2-ton truck moving 90 km/hr D) a 1-ton truck moving 110 km/hr E) A, B, C, and D all have the same kinetic energy. Answer: C 26) Of the temperature ranges below, which range represents the smallest range of actual temperature? A) 50-100° Kelvin B) 50-100° Celsius C) 50-100° Fahrenheit D) They all represent the same change in temperature. Answer: C 5 Copyright © 2014 Pearson Education, Inc.

27) Absolute zero is A) 0° Kelvin. B) 0° Celsius. C) 0° Fahrenheit. D) 32° Fahrenheit. E) 273° Celsius. Answer: A 28) What does temperature measure? A) the average mass of particles in a substance B) the average size of particles in a substance C) the average kinetic energy of particles in a substance D) the total number of particles in a substance E) the total potential energy of particles in a substance Answer: C 29) Suppose you heat up an oven and boil a pot of water. Which of the following explains why you would be burned by sticking your hand briefly in the pot but not by sticking your hand briefly in the oven? A) The oven has a higher temperature than the water. B) The water has a higher temperature than the oven. C) The oven has a higher heat content than the water. D) The molecules in the water are moving faster than the molecules in the oven. E) The water has a higher heat content than the oven. Answer: E 30) The amount of gravitational potential energy released as an object falls depends on A) its mass and the distance it falls. B) its mass and its speed at the time it begins falling. C) only the distance it falls. D) only its mass. E) only its speed at the time it begins falling. Answer: A 31) In the formula E = mc2, what does E represent? A) the kinetic energy of a moving object B) the radiative energy carried by light C) the gravitational potential energy of an object held above the ground D) the mass-energy, or potential energy stored in an object's mass E) the electric charge of the object Answer: D

32) Considering Einstein's famous equation, E = mc2, which of the following statements is true? A) Mass can be turned into energy, but energy cannot be turned back into mass. B) It takes a large amount of mass to produce a small amount of energy. C) A small amount of mass can be turned into a large amount of energy. D) You can make mass into energy if you can accelerate the mass to the speed of light. E) One kilogram of mass represents 1 joule of energy. Answer: C 33) Which of the following scenarios correctly demonstrates the transformation of mass into energy as given by Einstein's equation, E = mc2? A) When hydrogen is fused into helium, whether in the Sun or in a nuclear bomb, the mass difference is turned into energy. B) An object accelerated to a great speed has a lot of kinetic energy. C) A mass raised to a great height has a lot of gravitational potential energy. D) When you boil a pot of water, it has a high heat content, or thermal energy. E) A burning piece of wood produces light and heat, therefore giving off radiative and thermal energy. Answer: A 34) The ultimate source of energy that powers the Sun is A) chemical potential energy of hydrogen burning into helium. B) mass energy of hydrogen fusing into helium. C) gravitational potential energy of the contraction of the gas cloud that formed the Sun. D) kinetic energy of the orbital motion of the Sun. E) thermal energy of the hydrogen atoms in the Sun. Answer: B 35) Which of the following statements correctly describes the law of conservation of energy? A) An object always has the same amount of energy. B) Energy can change between many different forms, such as potential, kinetic, and thermal, but it is ultimately destroyed. C) The total quantity of energy in the universe never changes. D) The fact that you can fuse hydrogen into helium to produce energy means that helium can be turned into hydrogen to produce energy. E) It is not really possible for an object to gain or lose potential energy, because energy cannot be destroyed. Answer: C 36) Where does the energy come from that your body uses to keep you alive? A) It is produced from the radiative energy of the Sun on your skin. B) It comes from the foods you eat. C) It comes from the water you drink. D) It is in the air that you breathe. E) It is created during the time that you rest or sleep. Answer: B

37) When a rock is held above the ground, we say it has some potential energy. When we let it go, it falls and we say the potential energy is converted to kinetic energy. Finally, the rock hits the ground. What has happened to the energy? A) The energy goes into the ground and, as a result, the orbit of the earth about the Sun is slightly changed. B) The energy goes to producing sound and to heating the ground, rock, and surrounding air. C) The rock keeps the energy inside it (saving it for later use). D) It is lost forever. Energy does not have to be conserved. E) It is transformed back into gravitational potential energy. Answer: B 38) According to the universal law of gravitation, the force due to gravity is A) directly proportional to the square of the distance between objects. B) inversely proportional to the square of the distance between objects. C) directly proportional to the distance between objects. D) inversely proportional to the distance between objects. E) not dependent on the distance between objects. Answer: B 39) The force of gravity is an inverse square law. This means that, if you double the distance between two large masses, the gravitational force between them A) also doubles. B) strengthens by a factor of 4. C) weakens by a factor of 4. D) weakens by a factor of 2. E) is unaffected. Answer: C 40) According to the universal law of gravitation, if you triple the distance between two objects, then the gravitational force between them will A) increase by a factor of 3. B) decrease by a factor of 3. C) decrease by a factor of 6. D) increase by a factor of 9. E) decrease by a factor of 9. Answer: E 41) According to the universal law of gravitation, if you double the masses of both attracting objects, then the gravitational force between them will A) not change at all. B) increase by a factor of 2. C) decrease by a factor of 2. D) increase by a factor of 4. E) decrease by a factor of 4. Answer: D

42) The orbital period of a geosynchronous satellite is A) 23 hours 56 minutes. B) 24 hours. C) 365.25 days. D) 12 years. E) 26,000 years. Answer: A 43) The allowed shapes for orbits under the force of gravity are A) ellipses only. B) ellipses and spirals. C) ellipses, parabolas, and hyperbolas. D) ellipses, spirals, and parabolas. E) spirals, circles, and squares. Answer: C 44) Each of the following lists two facts. Which pair can be used with Newton's version of Kepler's third law to determine the mass of the Sun? A) Mercury is 0.387 AU from the Sun, and Earth is 1 AU from the Sun. B) The mass of Earth is 6 × 1024 kg, and Earth orbits the Sun in 1 year. C) Earth rotates in 1 day and orbits the Sun in 1 year. D) Earth is 150 million km from the Sun and orbits the Sun in 1 year. E) Jupiter is the most massive planet and has a mass of 1.9 × 1027 kg. Answer: D 45) According to what we now know from Newton's laws, which of the following best explains why Kepler's second law is true? A) A planet's angular momentum must be conserved as it moves around its orbit. B) Orbits must be elliptical in shape. C) Gravity is an inverse cube law. D) This effect happens because of the influence of other planets on a particular planet's orbit. Answer: A 46) The center of mass of a binary star system is A) the center of the most massive of the two stars. B) the center of the least massive of the two stars. C) the point halfway in between them. D) the point at which the two objects would balance if they were somehow connected. E) the average mass of the two stars. Answer: D

47) The mass of Jupiter can be calculated by A) measuring the orbital period and distance of Jupiter's orbit around the Sun. B) measuring the orbital period and distance of one of Jupiter's moons. C) measuring the orbital speed of one of Jupiter's moons. D) knowing the Sun's mass and measuring how Jupiter's speed changes during its elliptical orbit around the Sun. E) knowing the Sun's mass and measuring the average distance of Jupiter from the Sun. Answer: B 48) Which of the following best describes the origin of ocean tides on Earth? A) Tides are caused by the difference in the force of gravity exerted by the Moon across the sphere of the earth. B) The Moon's gravity pulls harder on water than on land, because water is less dense than rock. C) Tides are caused by the 23 1/2° tilt of the earth's rotational axis to the ecliptic plane. D) Tides are caused primarily by the gravitational force of the Sun. E) Tides are caused on the side of Earth nearest the Moon because the Moon's gravity attracts the water. Answer: A 49) The tides on Earth are an example of A) Newton's first law of motion. B) Newton's second law of motion. C) Newton's third law of motion. D) the universal law of gravitation. E) none of the above Answer: D 50) At which lunar phase(s) are tides most pronounced (e.g., the highest high tides)? A) first quarter B) new Moon C) full Moon D) both new and full Moons E) both first and third quarters Answer: D 51) At which lunar phase(s) are tides least pronounced (e.g., the lowest high tides)? A) first quarter B) new Moon C) full Moon D) both new and full Moons E) both first and third quarters Answer: E

52) Suppose a lone asteroid happens to be passing relatively near Jupiter (but not near any of its moons), following a hyperbolic orbit as it approaches Jupiter. Which of the following statements would be true? A) Jupiter's gravity would capture the asteroid, making it a new moon of Jupiter. B) The asteroid's orbit around Jupiter would not change, and it would go out on the same hyperbolic orbit that it came in on. C) Jupiter would probably expel the asteroid far out into the solar system. D) The asteroid would slowly spiral into Jupiter until it crashed into the atmosphere. E) Any of these scenarios is possible. Answer: B 53) A basketball player jumps to make a basket, and remains in the air for a moment. A sportscaster, talking about the game, then remarks that she has "defied gravity." Which of the following accurately describes the situation? A) The player did stay in the air in spite of the Law of Gravitation, but a single counterobservation is not enough to warrant revisiting a theory that usually works. B) The player produced enough force with her legs to accelerate up into the air, and gravity brought her back down with an acceleration of 9.8 m/s2. C) The player only seemed to defy gravity, but part of the Universal Law of Gravitation makes an exception for basketball players. D) The player has defied gravity, so scientists must go back into the lab to refine their theory. Answer: B 54) Imagine we've discovered a planet orbiting another star at 1 AU every 6 months. The planet has a moon that orbits the planet at the same distance as our Moon, but it takes 2 months. What can we infer about this planet? A) It is more massive than Earth. B) It is less massive than Earth. C) It has the same mass as Earth. D) We cannot answer the question without knowing the mass of the star. E) We cannot answer the question without knowing the mass of the moon. Answer: B 4.2 True/False Questions 1) Speed and velocity are the same thing. Answer: FALSE 2) The Moon is constantly falling toward Earth. Answer: TRUE 3) If you are driving at 30 miles per hour and increase your speed to 60 miles per hour, you quadruple your kinetic energy. Answer: TRUE

4) If you double the mass of fusion material in a hydrogen bomb, you quadruple the amount of energy generated. Answer: FALSE 5) When energy is converted from one form to another, a tiny amount is inevitably lost. Answer: FALSE 6) Kepler deduced his laws of planetary motion once Newton had published his universal law of gravitation. Answer: FALSE 7) The center of mass for Earth orbiting the Sun lies inside the Sun. Answer: TRUE 8) There is no gravity in space. Answer: FALSE 9) Doubling the distance between two objects halves the gravitational force between them. Answer: FALSE 10) The escape velocity from Earth is greater for larger rockets than for small ones. Answer: FALSE 11) Tidal friction caused by Earth's stretching from the Moon's gravity is gradually slowing down the rotation of Earth. Answer: TRUE 12) The Moon is slowly moving away from Earth. Answer: TRUE 13) Unbound orbits have more orbital energy than bound orbits. Answer: TRUE 14) Process of Science: Gravity only affects very massive objects and we can therefore only test theories about it when looking at the orbits of planets. Answer: FALSE

4.3 Short Answer Questions 1) Under what conditions is an object weightless? Answer: whenever it is in free-fall 2) State Newton's three laws of motion. Answer: 1. In the absence of a net force, an object moves with constant velocity. 2. Force = rate of change in momentum or mass times acceleration. 3. For every force there is an equal and opposite reaction force. 3) Give an example in which thermal energy might be converted to gravitational energy. Answer: A hot air balloon rises: as we heat the gas in a balloon, the internal pressure increases and the balloon expands. Therefore the density of the air inside decreases and when the average density of the entire balloon (balloon material plus basket plus air inside) becomes less than the density of air outside, the balloon rises, gaining gravitational energy. 4) Give an example in which kinetic energy can be converted to thermal energy. Answer: The brakes on a car: applying the brakes on a car slows it down through friction of the brake pads with the brake drums. The car slows down, losing kinetic energy, and the pads warm up, gaining thermal energy (try touching your wheels–but be careful because they can become very hot–after using your brakes for a long time, e.g., going down a steep mountain road).For the following questions, you may wish to refer to Newton's version of Kepler's third law: p2 = (Hint: You will not need a calculator for these problems.) 5) Imagine another solar system, with a star of the same mass as the Sun. Suppose there is a planet in that solar system with a mass of 2MEarth orbiting at a distance of 1 AU from the star. What (approximately) is the orbital period of this planet? Explain your answer. Answer: The orbital period of the planet would be approximately the same as that of the earth (1 year). Kepler's law considers only the sum of the object masses. In comparison with the mass of the star, the mass of the planet can be neglected. Thus, even though the planet is twice as massive as Earth, its orbit will be nearly the same as that of Earth. 6) Suppose a solar system has a star that is four times more massive than our Sun. If that solar system has a planet the same size as Earth, orbiting at a distance of 1 AU, what is the orbital period of the planet? Explain. Answer: From Kepler's law, we see that the period depends on the inverse square root of the object masses. Thus, if we have a star four times as massive as the Sun, the period of a planet orbiting at 1 AU will be half that of the earth, or 6 months.

7) Suppose it takes 6 seconds for a watermelon to fall to the ground after being dropped from a tall building. If there were no air resistance, so that the watermelon would fall with the acceleration of gravity, about how fast would it be going when it hit the ground? Answer: Since the acceleration of gravity is about 10 m/s2, the watermelon gains 10 m/s of speed every second it is in the air. Therefore, the watermelon would be going 60 m/s when it hit the ground. 8) The Moon orbits Earth in an average of 27.3 days at an average distance of 384,000 kilometers. Using Newton's version of Kepler's third law p2 =

determine the mass of Earth. You may neglect the mass of the Moon

in comparison to the mass of Earth. Answer: Using the Moon's orbital period and distance, the mass of Earth is about 6.0 × 1024 kg. MEarth ≈ Making sure that we use appropriate units, we find:

MEarth ≈ = 6.0 × 1024 kg 9) Explain how we can use Newton's version of Kepler's third law to measure the total mass of two stars in a binary system. Answer: By observing the stars with a telescope, you can measure how far they move apart from each other (their orbital distance, a) and how long it takes them to move around each other (their orbital period, p). Then you use the formula p2 =

to derive the total mass of the

two stars, M1 + M2. 10) Suppose a satellite is in a low-Earth orbit. Is it possible that the satellite will eventually fall to the ground? Why or why not? Answer: To fall to Earth, the satellite must lose some of its orbital energy. In low-Earth orbit, this can happen because the earth's atmosphere extends to high altitudes and exerts some atmospheric drag on the satellite.

11) Briefly explain why Earth feels a greater tidal force from the Moon than from the Sun, even though it feels a greater gravitational force from the Sun. Answer: Tidal force depends on the difference in the force of gravity across an object. For an object of a given size, the difference is greater when the attracting object is closer. The Moon is much closer to Earth than the Sun, which is why it exerts a greater tidal force. 12) Explain what synchronous rotation is. What is it caused by? Give an example. Answer: Synchronous rotation is when the rotational period of an object is the same as its orbital period around another object. As an object orbits another, it is stretched by the varying force of gravity across it. The resulting tidal bulges lag behind the rotation of the object slightly and cause it to rotate slower. This continues over time until the rotational period becomes the same as the orbital period, at which point there is no longer any tidal friction and the rotational and orbital periods are synchronized. An example is the Moon always presenting the same face to Earth through its orbit. A variation on this is Mercury which rotates 3 times for every 2 orbits around the Sun. 13) Process of Science: Why is it not science to start with the answer to a question and look for evidence to support it? Answer: The process of science involves asking a question and then forming testable hypotheses in order to gather evidence either to support or to refute it. So-called "cherry picking" of evidence to support an idea and ignoring evidence that may refute it does not advance knowledge and is not the scientific method. 14) Process of Science: Give some everyday examples that illustrate Newton's Laws of Motion. Answer: Many possibilities here. For example, ice skating (low friction demonstrates first law, changing direction requires pushing the opposite way demonstrates the third law); billiard balls hitting each other and exchanging momentum (first law). An accelerating car pushes you back in your seat (second law), etc. 4.4 Mastering Astronomy Reading Quiz 1) The difference between speed and velocity is that A) they are expressed in different units. B) velocity also includes a direction. C) velocity is the same as acceleration but speed is different. D) velocity is calculated using a physics equation. Answer: B 2) The acceleration of gravity on Earth is approximately 10 m/s2 (more precisely, 9.8 m/s2). If you drop a rock from a tall building, about how fast will it be falling after 3 seconds? A) 30 m/s. B) 10 m/s. C) 30 m/s2 D) 10 m/s2 E) 20 m/s Answer: A 15 Copyright © 2014 Pearson Education, Inc.

3) Momentum is defined as A) mass times velocity. B) mass times speed. C) force times velocity. D) mass times acceleration. Answer: A 4) Suppose you lived on the Moon. Which of the following would be true? A) Your weight would be less than your weight on Earth, but your mass would be the same as it is on Earth. B) Both your weight and your mass would be less than they are on Earth. C) Your mass would be less than your mass on Earth, but your weight would be the same as it is on Earth. D) Both your weight and your mass would be the same as they are on Earth. Answer: A 5) In which of the following cases would you feel weightless? A) while falling from a roof B) while parachuting from an airplane C) while accelerating downward in an elevator D) while walking on the Moon Answer: A 6) Which of the following statements is not one of Newton's Laws of Motion? A) What goes up must come down. B) The rate of change of momentum of an object is equal to the net force applied to the object. C) In the absence of a net force acting upon it, an object moves with constant velocity. D) For any force, there always is an equal and opposite reaction force. Answer: A 7) Newton's Second Law of Motion tells us that the net force applied to an object equals its A) mass times acceleration. B) mass times energy. C) momentum times velocity. D) mass times velocity. Answer: A 8) Suppose that two objects collide. Which of the following things is not the same both before and after the collision? A) the total temperature of the objects B) the total momentum of the objects C) the total angular momentum of the objects D) the total energy of the objects Answer: A

9) When a spinning ice skater pulls in his arms, he spins faster because A) his angular momentum must be conserved, so reducing his radius must increase his speed of rotation. B) there is less friction with the air. C) there is less friction with the ice. D) there exists an unbalanced reaction force. Answer: A 10) The energy attributed to an object by virtue of its motion is known as A) potential energy. B) kinetic energy. C) radiative energy. D) mass-energy. Answer: B 11) Radiative energy is A) heat energy. B) energy from nuclear power plants. C) energy carried by light. D) energy of motion. Answer: C 12) Absolute zero is A) 0 Kelvin. B) 0° Celsius. C) 0° Fahrenheit. D) 100° Celsius. Answer: A 13) What does temperature measure? A) the average mass of particles in a substance B) the total potential energy of particles in a substance C) the total amount of heat in a substance D) the average kinetic energy of particles in a substance Answer: D 14) In the formula E=mc2, what does E represent? A) the mass-energy, or potential energy stored in an object's mass B) the kinetic energy of a moving object C) the radiative energy carried by light D) the gravitational potential energy of an object held above the ground Answer: A

15) According to the universal law of gravitation, if you triple the distance between two objects, then the gravitational force between them A) increases by a factor of 9. B) decreases by a factor of 9. C) decreases by a factor of 3. D) increases by a factor of 3. Answer: B 16) What is the difference between a bound orbit and an unbound orbit around the Sun? A) A bound orbit is an orbit allowed by the universal law of gravitation, and an unbound orbit is not. B) An object on a bound orbit has a gravitational attraction to the Sun, while an object on an unbound orbit does not. C) A bound orbit is circular, while an unbound orbit is elliptical. D) An object on a bound orbit follows the same path around the Sun over and over, while an object on an unbound orbit approaches the Sun just once and then never returns. Answer: D 17) The allowed shapes for the orbits of objects responding only to the force of gravity are A) ellipses, parabolas, and hyperbolas. B) ellipses only. C) ellipses, spirals, and parabolas. D) circles and ellipses. Answer: A 18) Why is Newton's version of Kepler's third law so useful to astronomers? A) It allows us to calculate distances to distant objects. B) It can be used to determine the masses of many distant objects. C) It tells us that more-distant planets orbit the Sun more slowly. D) It explains why objects spin faster when they shrink in size. Answer: B 19) What do we mean by the orbital energy of an orbiting object (such as a planet, moon, or satellite)? A) Orbital energy is the sum of the object's kinetic energy and its gravitational potential energy as it moves through its orbit. B) Orbital energy is the object's kinetic energy as it moves through its orbit. C) Orbital energy is a measure of the object's speed as it moves through its orbit. D) Orbital energy is the amount of energy required for the object to leave orbit and escape into space. Answer: A

20) Which statement must be true in order for a rocket to travel from Earth to another planet? A) It must carry a lot of extra fuel. B) It must have very large engines. C) It must attain escape velocity from Earth. D) It must be launched from space, rather than from the ground. Answer: C 21) Approximately where is it currently high tide on Earth? A) on the portion of Earth facing directly toward the Moon and on the portion of Earth facing directly away from the Moon B) only on the portion of the Earth facing directly toward the Moon C) wherever it is currently noon D) anywhere that ocean water laps upon the shore Answer: A 4.5 Mastering Astronomy Concept Quiz 1) Which of the following represents a case in which you are not accelerating? A) driving in a straight line at 60 miles per hour B) going from 0 to 60 miles per hour in 10 seconds C) slamming on the brakes to come to a stop at a stop sign D) driving 60 miles per hour around a curve Answer: A 2) Suppose you drop a 10-pound weight and a 5-pound weight on the Moon, both from the same height at the same time. What will happen? A) Both will hit the ground at the same time. B) The 10-pound weight will hit the ground before the 5-pound weight. C) The 5-pound weight will hit the ground before the 10-pound weight. D) Both weights will float freely, since everything is weightless on the Moon. Answer: A 3) Why are astronauts weightless in the Space Station? A) because the Space Station is traveling so fast B) because the Space Station is constantly in free-fall around Earth C) because there is no gravity in space D) because the Space Station is moving at constant velocity Answer: B 4) A net force acting on an object will always cause a change in the object's A) momentum. B) speed. C) mass. D) direction. Answer: A

5) Suppose you are in an elevator that is traveling upward at constant speed. How does your weight compare to your normal weight on the ground? A) It is greater. B) It is less. C) It is the same. D) You are weightless. Answer: C 6) The planets never travel in a straight line as they orbit the Sun. According to Newton's second law of motion, this must mean that A) the planets are always accelerating. B) the planets have angular momentum. C) the planets will eventually fall into the Sun. D) a force is acting on the planets. Answer: D 7) Suppose the Sun were suddenly to shrink in size but that its mass remained the same. According to the law of conservation of angular momentum, what would happen? A) The Sun would rotate faster than it does now. B) The Sun's rate of rotation would slow. C) The Sun's angular size in our sky would stay the same. D) This could never happen, because it is impossible for an object to shrink in size without an outside torque. Answer: A 8) Suppose you kick a soccer ball straight up to a height of 10 meters. Which of the following is true about the gravitational potential energy of the ball during its flight? A) The ball's gravitational potential energy is greatest at the instant it returns to hit the ground. B) The ball's gravitational potential energy is greatest at the instant when the ball is at its highest point. C) The ball's gravitational potential energy is always the same. D) The ball's gravitational potential energy is greatest at the instant the ball leaves your foot. Answer: B 9) Suppose you heat an oven to 400°F and boil a pot of water. Which of the following explains why you would be burned by sticking your hand briefly in the pot but not by sticking your hand briefly in the oven? A) The water can transfer heat to your arm more quickly than the air. B) The water has a higher temperature than the oven. C) The molecules in the water are moving faster than the molecules in the oven. D) The oven has a higher temperature than the water. Answer: A

10) Which of the following scenarios involves energy that we would typically calculate with Einstein's formula E=mc2? A) A small amount of the hydrogen in of a nuclear bomb becomes energy as fusion converts the hydrogen to helium. B) An object accelerated to a great speed has a lot of kinetic energy. C) A mass raised to a great height has a lot of gravitational potential energy. D) A burning piece of wood produces light and heat, therefore giving off radiative and thermal energy. Answer: A 11) A rock held above the ground has potential energy. As the rock falls, this potential energy is converted to kinetic energy. Finally, the rock hits the ground and stays there. What has happened to the energy? A) The energy goes to producing sound and to heating the ground, rock, and surrounding air. B) The energy goes into the ground, and as a result, the orbit of the Earth about the Sun is slightly changed. C) The rock keeps the energy inside it in the form of mass-energy. D) It is transformed back into gravitational potential energy. Answer: A 12) Suppose that the Sun shrank in size but that its mass remained the same. What would happen to Earth's orbit? A) The size of Earth's orbit would shrink, and it would take less than one year to orbit the Sun. B) Earth's orbit would expand, and it would take more than one year to orbit the Sun. C) Earth's orbit would be unaffected. D) Earth would change from a bound orbit to an unbound orbit and fly off into interstellar space. Answer: C 13) Imagine another solar system, with a star of the same mass as the Sun. Suppose a planet with a mass twice that of Earth (2MEarth) orbits at a distance of 1 AU from the star. What is the orbital period of this planet? A) 1 year B) 6 months C) 2 years D) It cannot be determined from the information given. Answer: A 14) Imagine another solar system, with a star more massive than the Sun. Suppose a planet with the same mass as Earth orbits at a distance of 1 AU from the star. How would the planet's year (orbital period) compare to Earth's year? A) The planet's year would be longer than Earth's. B) The planet's year would be shorter than Earth's. C) The planet's year would be the same as Earth's. D) An orbit at a distance of 1 AU would not be possible around a star more massive than the Sun. Answer: B 21 Copyright © 2014 Pearson Education, Inc.

15) Newton showed that Kepler's laws are A) natural consequences of the law of universal gravitation. B) seriously in error. C) actually only three of seven distinct laws of planetary motion. D) the key to proving that Earth orbits our Sun. Answer: A 16) Each of the following lists two facts. Which pair of facts can be used with Newton's version of Kepler's third law to determine the mass of the Sun? A) Earth is 150 million km from the Sun and orbits the Sun in one year. B) Mercury is 0.387 AU from the Sun and Earth is 1 AU from the Sun. C) The mass of Earth is 6 × 1024 kg and Earth orbits the Sun in one year. D) Earth rotates in one day and orbits the Sun in one year. Answer: A 17) When space probe Voyager 2 passed by Saturn, its speed increased (but not due to firing its engines). What must have happened? A) Voyager 2 must have dipped through Saturn's atmosphere. B) Saturn's rotation must have sped up slightly. C) Saturn must have lost a very tiny bit of its orbital energy. D) Saturn must have captured an asteroid at precisely the moment that Voyager 2 passed by. Answer: C 18) Suppose that a lone asteroid happens to be passing Jupiter on an unbound orbit (well above Jupiter's atmosphere and far from all of Jupiter's moons.) Which of the following statements would be true? A) The asteroid's orbit around Jupiter would not change, and it would go out on the same unbound orbit that it came in on. B) Jupiter's gravity would capture the asteroid, making it a new moon of Jupiter. C) Jupiter's gravity would suck in the asteroid, causing it to crash into Jupiter. D) There is no way to predict what would happen. Answer: A 19) Which of the following best describes the origin of ocean tides on Earth? A) Tides are caused by the difference in the force of gravity exerted by the Moon across the sphere of Earth. B) The Moon's gravity pulls harder on water than on land, because water is less dense than rock. C) Tides are caused by the 23.5-degree tilt of the Earth's rotational axis to the ecliptic plane. D) Tides are caused on the side of the Earth nearest the Moon because the Moon's gravity attracts the water. Answer: A

20) At which lunar phase(s) are tides most pronounced (for example, the highest high tides)? A) both first and third quarters B) both new and full Moons C) full Moon only D) new Moon only E) third quarter Moon only Answer: B 21) Which of the following best explains why the Moon's orbital period and rotation period are the same? A) The Moon once rotated faster, but tidal friction slowed the rotation period until it matched the orbital period. B) The Moon was once closer to Earth, but the force of gravity got weaker as the Moon moved farther away. C) The law of conservation of angular momentum ensured that the Moon must have the same amount of rotational angular momentum as it has of orbital angular momentum. D) The equality of the Moon's orbital and rotation periods is an extraordinary astronomical coincidence. Answer: A 22) Suppose the Moon's orbit were unchanged, but it rotated faster (meaning it did not have synchronous rotation). Which of the following would be true? A) The Moon would go through its cycle of phases (from one new Moon to the next) in less time than it does now. B) We would no longer always see nearly the same face of the Moon. C) Tides would be stronger; that is, higher high tides and lower low tides. D) High tides would occur more frequently than they do now. E) All of the above are true. Answer: B

The Cosmic Perspective, 7e (Bennett et al.) Chapter 5 Light and Matter: Reading Messages from the Cosmos 5.1 Multiple-Choice Questions 1) If you have a 100-watt light bulb, how much energy does it use each minute? A) 6,000 joules B) 6,000 watts C) 600 joules D) 600 watts E) 100 joules Answer: A 2) If a material is highly opaque, then it A) reflects most light. B) absorbs most light. C) transmits most light. D) scatters most light. E) emits most light. Answer: B 3) When light reflects off an object, what is the relation between the angle of incidence and the angle of reflection? A) angle of incidence = angle of reflection B) angle of incidence + angle of reflection = 90° C) angle of incidence + angle of reflection = 180° D) angle of incidence - angle of reflection = 90° E) It depends on the material that the light reflects off. Answer: A 4) If a material is transparent, then it A) reflects light well. B) absorbs light well. C) transmits light well. D) scatters light well. E) emits light well. Answer: C 5) Grass (that is healthy) looks green because A) it emits green light and absorbs other colors. B) it absorbs green light and emits other colors. C) it transmits green light and emits other colors. D) it reflects green light and absorbs other colors. Answer: D

6) Everything looks red through a red filter because A) the filter emits red light and absorbs other colors. B) the filter absorbs red light and emits other colors. C) the filter transmits red light and absorbs other colors. D) the filter reflects red light and transmits other colors. Answer: C 7) Which of the following cannot be described by a field? A) gravitational forces B) electrical forces C) magnetic forces D) radiation pressure Answer: D 8) The frequency of a wave is A) the number of peaks passing by any point each second. B) measured in cycles per second. C) measured in hertz (Hz). D) equal to the speed of the wave divided by the wavelength of the wave. E) all of the above Answer: E 9) The wavelength of a wave is A) how strong the wave is. B) the distance between a peak of the wave and the next trough. C) the distance between two adjacent peaks of the wave. D) the distance between where the wave is emitted and where it is absorbed. E) equal to the speed of the wave times the wave's frequency. Answer: C 10) How are wavelength, frequency, and energy related for photons of light? A) Longer wavelength means lower frequency and lower energy. B) Longer wavelength means higher frequency and lower energy. C) Longer wavelength means higher frequency and higher energy. D) Longer wavelength means lower frequency and higher energy. E) There is no simple relationship because different photons travel at different speeds. Answer: A 11) From lowest energy to highest energy, which of the following correctly orders the different categories of electromagnetic radiation? A) infrared, visible light, ultraviolet, X rays, gamma rays, radio B) radio, infrared, visible light, ultraviolet, X rays, gamma rays C) visible light, infrared, X rays, ultraviolet, gamma rays, radio D) gamma rays, X rays, visible light, ultraviolet, infrared, radio E) radio, X rays, visible light, ultraviolet, infrared, gamma rays Answer: B 2 Copyright © 2014 Pearson Education, Inc.

15) What are the three types of pressure that can push against the inward force of gravity? Explain what causes each pressure and where it would be likely to occur. Answer: (1) Thermal pressure occurs when the particles inside a star are heated enough so that their random motions cause an outward pressure. The two energy sources of internal thermal pressure are gravitational contraction, found in protostars and when a star has used up a fusionable material in its core, and nuclear fusion, which can occur in the core or in a shell of a star. (2) Degeneracy pressure arises from the idea of quantum mechanics that two electrons (or neutrons) cannot occupy the same state. Degeneracy pressure occurs in the cores of low-mass stars before a helium flash, maintains equilibrium in white dwarfs and neutron stars, and may be present immediately before a supernova event. (3) Radiation pressure exists only in massive stars where fusion rates are so high that photons transfer momentum to the surrounding gas and apply a third kind of pressure. 16) Briefly summarize the stages of life for a low-mass star. Answer: The protostar assembles from the molecular clouds, heats up from gravitational contraction, and begins hydrogen fusion in the core. The star settles onto the main sequence, where it will fuse hydrogen in its core for 10 billion years. When the core hydrogen is used up, the core contracts until it is degenerate, hydrogen fusion continues in a shell outside the core, and the outer layers expand and cool the star becomes a red giant. Helium fusion begins in the core, but since the core is degenerate a helium flash takes place and rapidly spreads throughout the core. Helium fusion stabilizes, and the star moves left on the H-R diagram. Core helium is used up and helium begins fusing in a shell outside the core, with hydrogen still fusing in a shell above it. The outer layers expand, and the star again becomes a red giant. The star undergoes thermal pulses and loses its outer layers through a stellar wind. The core shrinks and heats up but is not able to fuse any more elements. The star becomes a planetary nebula as heat from the core blows away and heats up the gas left over from the red giant phase. Only the naked degenerate core is left, a white dwarf. 17) Briefly summarize the stages of life for a high-mass star. Answer: The first stages are similar to those of a low-mass star, except that they happen over much shorter time periods. While on the main sequence, the star fuses hydrogen by the CNO cycle and remains at this stage only for several million years. In addition to helium fusion, highmass stars also undergo alpha-capture, which creates heavier elements by fusing a helium nucleus with an existing atom. After helium is used up in the core, the core contracts while helium and hydrogen fusion continue in outer shells. The core contracts until carbon ignition occurs, and the star moves left again on the H-R diagram while carbon fusion occurs in the core. The process continues for stars of still higher mass, zigzagging across the H-R diagram as heavier elements are fused in the core and used up as fuel. Each fusion stage requires less time until iron is finally produced in the core. Iron cannot be fused to produce energy, so the core collapses and pressures increase so that electrons and protons are converted to neutrons. A high quantity of neutrinos is released, which may help force the outer layers violently outward in an explosion called a supernova. Elements heavier than iron are created, the outer layers move away from the core at great velocities, and only a neutron star or black hole is left as a remnant.

18) Briefly explain why high-mass stars have shorter lifetimes than low-mass stars. Answer: High-mass stars have 10 to 100 times more mass (fuel) than a typical low-mass star. This greater mass produces a much higher downward gravitational pressure, leading to much higher core temperatures and higher rates of fusion. The luminosity of such stars is therefore 1,000 to 1 million times greater than in low-mass stars. So, although high-mass stars have more fuel to burn, they burn it at a much higher rate and therefore run out of fuel much more quickly. 19) Process of Science: Based on what you learned in this chapter, would you expect life to be able to evolve around first-generation stars in our universe? Why or why not? Answer: Most would say no, as the first-generation stars should not have yet been enriched with the heavy elements we believe are necessary for life. A student could also argue that life could form without these and our current understanding of life is incomplete. 20) Process of Science: Explain how patterns in cosmic abundances (Fig 12.15) fit theoretical predictions for the origin of the elements. Answer: Heavier elements are rarer as they are produced in shorter-lived phases of rare, massive stars. Iron is relatively abundant because its production is energetically favored as the end step of fusion and there is only a short time during the supernova phase when it can be destroyed by fission. The abundances of nuclei with even numbers of protons is greater than neighboring nuclei with odd numbers of protons as expected for nuclear reactions through the addition of helium nuclei. 21) Process of Science: How do observations of stars help us understand the theory of atomic nuclei? Answer: Many nuclear reactions occur during the late stages of stellar evolution. By observing how stars evolve and the production of different elements, we can learn about how nuclei react. 17.4 Mastering Astronomy Reading Quiz 1) Which of the following stars will live longest? A) a 1-solar-mass star B) a 2-solar-mass star C) a 3-solar-mass star D) a 4-solar-mass star E) a 5-solar-mass star Answer: A 2) In the context of understanding stellar lives, "high-mass" stars have masses A) more than about 8 times the mass of our Sun. B) more than about 3 times the mass of our Sun. C) more than twice the mass of our Sun. D) more than 20 times the mass of our Sun. Answer: A

3) Which of the following lists the stages of life for a low-mass star in the correct order? A) protostar, main-sequence star, red giant, planetary nebula, white dwarf B) protostar, main-sequence star, red giant, supernova, neutron star C) protostar, main-sequence star, planetary nebula, red giant D) main-sequence star, white dwarf, red giant, planetary nebula, protostar Answer: A 4) What happens when a main-sequence star exhausts its core hydrogen fuel supply? A) The entire star shrinks in size. B) The core shrinks while the rest of the star expands. C) The core immediately begins to fuse its helium into carbon. D) The star becomes a neutron star. Answer: B 5) The main source of energy for a star as it grows in size to become a red giant is A) hydrogen fusion in the central core. B) helium fusion in the central core. C) hydrogen fusion in a shell surrounding the central core. D) gravitational contraction. Answer: C 6) The overall helium fusion reaction is A) three helium nuclei fuse to form one carbon nucleus. B) two helium nuclei fuse to form one beryllium nucleus. C) two hydrogen nuclei fuse to form one helium nucleus. D) four helium nuclei fuse to form one oxygen nucleus. Answer: A 7) What is a helium flash? A) The ignition of helium shell burning in a high-mass star with a carbon core. B) A sudden brightening of a low-mass star, detectable from Earth by observing spectral lines of helium. C) It is another name for the helium fusion reaction. D) The sudden onset of helium fusion in the core of a low-mass star. Answer: D 8) An H-R diagram for a globular cluster will show a horizontal branch—a line of stars above the main-sequence but to the left of the subgiants and red giants. Which of the following statements about these horizontal branch stars is true? A) They have inert (non-burning) carbon cores. B) Their sole source of energy is hydrogen shell burning. C) They generate energy through both hydrogen fusion and helium fusion. D) In a particular star cluster, all horizontal branch stars have the same spectral type. Answer: C

9) What is a planetary nebula? A) gas created from the remains of planets that once orbited a dead star B) interstellar gas from which planets are likely to form in the not-too-distant future C) the remains of a high-mass star that has exploded D) gas ejected from a low-mass star in the final stage of its life Answer: D 10) The ultimate fate of our Sun is to A) explode in a supernova. B) become a white dwarf that will slowly cool with time. C) become a rapidly spinning neutron star. D) become a black hole. Answer: B 11) Which low-mass star does not have fusion occurring in its central core? A) a main-sequence star B) a red giant C) a helium-burning star Answer: B 12) How are low-mass red giant stars important to our existence? A) These stars manufactured virtually all the elements out of which we and our planet are made. B) These stars generate the energy that makes life on Earth possible. C) These stars manufactured most of the carbon atoms in our bodies. D) These stars provide most of the light that reaches us from globular clusters. Answer: C 13) Which of the following pairs of atomic nuclei would feel the strongest repulsive electromagnetic force if you tried to push them together? A) helium and helium B) hydrogen and hydrogen C) hydrogen and helium D) hydrogen and deuterium Answer: A 14) Which of the following stars will certainly end its life in a supernova? A) the Sun B) a red giant star C) a 10-solar-mass star D) a neutron star Answer: C

15) What is the CNO cycle? A) a set of steps by which four hydrogen nuclei fuse into one helium nucleus B) the process by which helium is fused into carbon, nitrogen, and oxygen C) the process by which carbon is fused into nitrogen and oxygen D) the set of fusion reactions that have produced all the carbon, nitrogen, and oxygen in the universe Answer: A 16) In order to predict whether a star will eventually fuse oxygen into a heavier element, what do you need to know about the star? A) its luminosity B) its overall abundance of elements heavier than helium C) how much oxygen it now has in its core D) its mass Answer: D 17) Why is iron significant to understanding how a supernova occurs? A) Iron is the heaviest of all atomic nuclei, and thus no heavier elements can be made. B) Supernovae often leave behind neutron stars, which are made mostly of iron. C) The fusion of iron into uranium is the reaction that drives a supernova explosion. D) Iron cannot release energy either by fission or fusion. Answer: D 18) After a supernova explosion, the remains of the stellar core A) will always be a neutron star. B) be either a neutron star or a black hole. C) will always be a black hole. D) may be either a white dwarf, neutron star, or black hole Answer: B 19) Why is Supernova 1987A particularly important to astronomers? A) It is the nearest supernova to have occurred at a time when we were capable of studying it carefully with telescopes. B) It was the first supernova detected in nearly 400 years. C) It provided the first evidence that supernovae really occur. D) It occurred only a few light-years from Earth. Answer: A 20) Algol consist of a 3.7 MSun main-sequence star and a 0.8 MSun subgiant. Why does this seem surprising, at least at first? A) The two stars in a binary system should both be at the same stage of life; that is, they should either both be main-sequence stars or both be subgiants. B) It doesn't make sense to find a subgiant in a binary star system. C) The two stars should be the same age, so we'd expect the subgiant to be more massive than the main-sequence star. D) A star with a mass of 3.7 MSun is too big to be a main-sequence star. Answer: C 18 Copyright © 2014 Pearson Education, Inc.

21) Where does gold (the element) come from? A) It is produced by mass transfer in close binaries. B) It is produced during the supernova explosions of high-mass stars. C) It is produced during the late stages of fusion in low-mass stars. D) It was produced during the Big Bang. Answer: B 17.5 Mastering Astronomy Concept Quiz 1) Sun is considered to be a A) low-mass star. B) intermediate-mass star C) high-mass star. D) brown dwarf. Answer: A 2) Which of the following types of data provide evidence that helps us understand the life tracks of low-mass stars? A) H-R diagrams of open clusters B) observing a low-mass star over many years C) H-R diagrams of globular clusters D) spacecraft observations of the Sun Answer: C 3) Why is a 1 solar-mass red giant more luminous than a 1 solar-mass main-sequence star? A) The red giant has a hotter core. B) The red giant's surface is hotter. C) The red giant is more massive. D) Fusion reactions are producing energy at a greater rate in the red giant. Answer: D 4) Which of the following describes a star with a hydrogen-burning shell and an inert helium core? A) It is a red giant that grows in luminosity until it dies in a planetary nebula. B) It is a subgiant that gradually grows dimmer as its hydrogen-burning shell expands and cools. C) It is a subgiant that grows in luminosity until helium fusion begins in the central core. D) It is what is known as a helium-burning star, which has both helium fusion in its core and hydrogen fusion in a shell. Answer: C

5) Which of the following observations would not be likely to provide information about the final, explosive stages of a star's life? A) studying the light rings around Supernova 1987A in the Large Magellanic Cloud B) decades of continuous monitoring of red giants in a globular cluster C) observing the structures of planetary nebulae D) neutrino detections from nearby supernovae Answer: B 6) Which is more common: a star blows up as a supernova, or a star forms a planetary nebula/white dwarf system? A) Supernovae are more common. B) Planetary nebula formation is more common. C) They both occur in about equal numbers. D) It is impossible to say. Answer: B This diagram represents the life track of a 1-solar-mass star. Refer to the life stages labeled with Roman numerals.

7) During which stage is the star's energy supplied by primarily by gravitational contraction? A) II B) III C) V D) VI E) VII Answer: A 8) During which stage does the star have an inert (non-burning) helium core? A) III B) IV C) VI D) VII E) VIII Answer: B

9) Which stage lasts the longest? A) I B) VI C) III D) VIII Answer: C 10) During which stage does the star have an inert (non-burning) carbon core surrounded by shells of helium and hydrogen burning? A) II B) III C) VI D) VII E) VIII Answer: E 11) What will happen to the star after stage VIII? A) Its outer layers will be ejected as a planetary nebula and its core will become a white dwarf. B) It will continue to expand gradually until carbon fusion begins in its core. C) It will explode as a supernova and leave a neutron star or black hole behind. D) It will remain in stage VIII for about 10 billion years, after which its outer layers will shrink back and cool. Answer: A 12) Carbon fusion occur in high-mass stars but not in low-mass stars because A) the cores of low-mass stars never contain significant amounts of carbon. B) the cores of low-mass stars never get hot enough for carbon fusion. C) only high-mass stars do fusion by the CNO cycle. D) carbon fusion can occur only in the stars known as carbon stars. Answer: B 13) Which of the following statements about various stages of core nuclear burning (hydrogen, helium, carbon, etc.) in a high-mass star is not true? A) As each stage ends, the core shrinks and heats further. B) Each successive stage creates an element with a higher atomic number and atomic mass number. C) As each stage ends, the reactions that occurred in previous stages continue in shells around the core. D) Each successive stage lasts for approximately the same amount of time. Answer: D 14) Which event marks the beginning of a supernova? A) the sudden collapse of an iron core into a compact ball of neutrons B) the onset of helium burning after a helium flash C) the beginning of neon burning in an extremely massive star D) the sudden initiation of the CNO cycle Answer: A 21 Copyright © 2014 Pearson Education, Inc.

15) Suppose that the star Betelgeuse (the upper left shoulder of Orion) were to supernova tomorrow (as seen here on Earth). What would it look like to the naked eye? A) Betelgeuse would remain a dot of light, but would suddenly become so bright that, for a few weeks, we'd be able to see this dot in the daytime. B) We'd see a cloud of gas expanding away from the position where Betelgeuse used to be. Over a period of a few weeks, this cloud would fill our entire sky. C) Because the supernova destroys the star, Betelgeuse would suddenly disappear from view. D) Betelgeuse would suddenly appear to grow larger in size, soon reaching the size of the full Moon. It would also be about as bright as the full Moon. Answer: A 16) Suppose that hydrogen, rather than iron, had the lowest mass per nuclear particle. Which of the following would be true? A) Stars would be brighter. B) Stars would be less massive. C) All stars would be red giants. D) Nuclear fusion could not power stars. Answer: D 17) Observations show that elements with atomic mass numbers divisible by 4 (such as oxygen16, neon-20, and magnesium-24) tend to be more abundant in the universe than elements with atomic mass numbers in between. Why do we think this is the case? A) The apparent pattern is thought to be a random coincidence. B) Elements with atomic mass numbers divisible by 4 tend to be more stable than elements in between. C) At the end of a high-mass star's life, it produces new elements through a series of helium capture reactions. D) This pattern in elemental abundances was apparently determined during the first few minutes after the Big Bang. Answer: C 18) A spinning neutron star has been observed at the center of a A) planetary nebula. B) supernova remnant. C) red supergiant. D) protostar. Answer: B

19) You discover a binary star system in which one star is a 15 MSun main-sequence star and the other is a 10 MSun giant. How do we think that a star system such as this might have come to exist? A) The giant must once have been the more massive star, but is now less massive because it transferred some of its mass to its companion. B) Although both stars probably formed from the same clump of gas, the more massive one must have had its birth slowed so that it became a main-sequence stars millions of years later than its less massive companion. C) The two stars probably were once separate, but became a binary when a close encounter allowed their mutual gravity to pull them together. D) The two stars are simply evolving normally and independently, and one has become a giant before the other. Answer: A 20) Tidal forces are very important to the Algol system today, but were not important when both stars were still on the main sequence. Why not? A) Main-sequence stars in a system like the Algol system are small compared to their physical separation. B) Main-sequence stars are too big to be affected by tidal forces. C) Main-sequence stars are too massive to be affected by tidal forces. D) Main-sequence stars are unaffected by tidally-induced mass transfer. Answer: A

The Cosmic Perspective, 7e (Bennett et al.) Chapter 18 The Bizarre Stellar Graveyard 18.1 Multiple-Choice Questions 1) Degeneracy pressure is the source of the pressure that stops the crush of gravity in all the following except A) a brown dwarf. B) a white dwarf. C) a neutron star. D) a very massive main-sequence star. E) the central core of the Sun after hydrogen fusion ceases but before helium fusion begins. Answer: D 2) White dwarfs are so called because A) they are both very hot and very small. B) they are the end-products of small, low-mass stars. C) they are the opposite of black holes. D) it amplifies the contrast with red giants. E) they are supported by electron degeneracy pressure. Answer: A 3) A teaspoonful of white dwarf material on Earth would weigh A) the same as a teaspoonful of Earth-like material. B) about the same as Mt. Everest. C) about the same as Earth. D) a few tons. E) a few million tons. Answer: D 4) Which of the following is closest in mass to a white dwarf? A) the Moon B) Earth C) Jupiter D) Neptune E) the Sun Answer: E

5) Why is there an upper limit to the mass of a white dwarf? A) White dwarfs come only from stars smaller than 1.4 solar masses. B) The more massive the white dwarf, the greater the degeneracy pressure and the faster the speeds of its electrons. Near 1.4 solar masses, the speeds of the electrons approach the speed of light, so more mass cannot be added without breaking the degeneracy pressure. C) The more massive the white dwarf, the higher its temperature and hence the greater its degeneracy pressure. At about 1.4 solar masses, the temperature becomes so high that all matter effectively melts, even individual subatomic particles. D) The upper limit to the masses of white dwarfs was determined through observations of white dwarfs, but no one knows why the limit exists. E) Above this mass, the electrons would be pushed together so closely they would turn into neutrons and the star would become a neutron star. Answer: B 6) What is the ultimate fate of an isolated white dwarf? A) It will cool down and become a cold black dwarf. B) As gravity overwhelms the electron degeneracy pressure, it will explode as a nova. C) As gravity overwhelms the electron degeneracy pressure, it will explode as a supernova. D) As gravity overwhelms the electron degeneracy pressure, it will become a neutron star. E) The electron degeneracy pressure will eventually overwhelm gravity and the white dwarf will slowly evaporate. Answer: A 7) Suppose a white dwarf is gaining mass because of accretion in a binary system. What happens if the mass someday reaches the 1.4-solar-mass limit? A) The white dwarf undergoes a catastrophic collapse, leading to a type of supernova that is somewhat different from that which occurs in a massive star but is comparable in energy. B) The white dwarf, which is made mostly of carbon, suddenly becomes much hotter in temperature and therefore is able to begin fusing the carbon. This turns the white dwarf back into a star supported against gravity by ordinary pressure. C) The white dwarf immediately collapses into a black hole, disappearing from view. D) A white dwarf can never gain enough mass to reach the limit because a strong stellar wind prevents the material from reaching it in the first place. Answer: A 8) Which of the following statements about novae is not true? A) A star system that undergoes a nova may have another nova sometime in the future. B) A nova involves fusion taking place on the surface of a white dwarf. C) Our Sun will probably undergo at least one nova when it becomes a white dwarf about 5 billion years from now. D) When a star system undergoes a nova, it brightens considerably, but not as much as a star system undergoing a supernova. E) The word nova means "new star" and originally referred to stars that suddenly appeared in the sky, then disappeared again after a few weeks or months. Answer: C

9) What kind of pressure supports a white dwarf? A) neutron degeneracy pressure B) electron degeneracy pressure C) thermal pressure D) radiation pressure E) all of the above Answer: B 10) What is the upper limit to the mass of a white dwarf? A) There is no upper limit. B) There is an upper limit, but we do not yet know what it is. C) 2 solar masses D) 1.4 solar masses E) 1 solar mass Answer: D 11) How does a 1.2-solar-mass white dwarf compare to a 1.0-solar-mass white dwarf? A) It has a larger radius. B) It has a smaller radius. C) It has a higher surface temperature. D) It has a lower surface temperature. E) It is supported by neutron, rather than electron, degeneracy pressure. Answer: B 12) Which of the following is closest in size (radius) to a white dwarf? A) Earth B) a small city C) a football stadium D) a basketball E) the Sun Answer: A 13) What kind of star is most likely to become a white-dwarf supernova? A) an O star B) a star like our Sun C) a binary M star D) a white dwarf star with a red giant binary companion E) a pulsar Answer: D

14) Observationally, how can we tell the difference between a white-dwarf supernova and a massive-star supernova? A) A massive-star supernova is brighter than a white-dwarf supernova. B) A massive-star supernova happens only once, while a white-dwarf supernova can repeat periodically. C) The spectrum of a massive-star supernova shows prominent hydrogen lines, while the spectrum of a white-dwarf supernova does not. D) The light of a white-dwarf supernova fades steadily, while the light of a massive-star supernova brightens for many weeks. E) We cannot yet tell the difference between a massive-star supernova and a white-dwarf supernova. Answer: C 15) After a massive-star supernova, what is left behind? A) always a white dwarf B) always a neutron star C) always a black hole D) either a white dwarf or a neutron star E) either a neutron star or a black hole Answer: E 16) A teaspoonful of neutron star material on Earth would weigh A) about the same as a teaspoonful of Earth-like material. B) a few tons. C) more than Mt. Everest. D) more than the Moon. E) more than Earth. Answer: C 17) Which of the following is closest in size (radius) to a neutron star? A) Earth B) a city C) a football stadium D) a basketball E) the Sun Answer: B

18) Which of the following best describes what would happen if a 1.5-solar-mass neutron star, with a diameter of a few kilometers, were suddenly (for unexplained reasons) to appear in your hometown? A) The entire mass of Earth would end up as a thin layer, about 1 cm thick, over the surface of the neutron star. B) It would rapidly sink to the center of Earth. C) The combined mass of Earth and the neutron star would cause the neutron star to collapse into a black hole. D) It would crash through Earth, creating a large crater, and exit Earth on the other side. E) It would crash into Earth, throwing vast amounts of dust into the atmosphere which in turn would cool Earth. Such a scenario is probably what caused the extinction of the dinosaurs. Answer: A 19) From an observational standpoint, what is a pulsar? A) a star that slowly changes its brightness, getting dimmer and then brighter with a period of anywhere from a few hours to a few weeks B) an object that emits flashes of light several times per second or more, with near perfect regularity C) an object that emits random "pulses" of light that sometimes occur only a fraction of a second apart and other times stop for several days at a time D) a star that changes color rapidly, from blue to red and back again E) a star that rapidly changes size as it moves off the main sequence Answer: B 20) From a theoretical standpoint, what is a pulsar? A) a star that alternately expands and contracts in size B) a rapidly rotating neutron star C) a neutron star or black hole that happens to be in a binary system D) a binary system that happens to be aligned so that one star periodically eclipses the other E) a star that is burning iron in its core Answer: B 21) What causes the radio pulses of a pulsar? A) The star vibrates. B) As the star spins, beams of radio radiation sweep through space. If one of the beams crosses Earth, we observe a pulse. C) The star undergoes periodic explosions of nuclear fusion that generate radio emission. D) The star's orbiting companion periodically eclipses the radio waves emitted by the main pulsar. E) A black hole near the star absorbs energy and re-emits it as radio waves. Answer: B

22) How do we know that pulsars are neutron stars? A) We have observed massive-star supernovae produce pulsars. B) Pulsars and neutron stars look exactly the same. C) No massive object, other than a neutron star, could spin as fast as we observe pulsars spin. D) Pulsars have the same upper mass limit as neutron stars do. E) none of the above Answer: C 23) What is the ultimate fate of an isolated pulsar? A) It will spin ever faster, becoming a millisecond pulsar. B) As gravity overwhelms the neutron degeneracy pressure, it will explode as a supernova. C) As gravity overwhelms the neutron degeneracy pressure, it will become a white dwarf. D) It will slow down, the magnetic field will weaken, and it will become invisible. E) The neutron degeneracy pressure will eventually overwhelm gravity and the pulsar will slowly evaporate. Answer: D 24) What is the basic definition of a black hole? A) any compact mass that emits no light B) a dead star that has faded from view C) any object from which the escape velocity exceeds the speed of light D) any object made from dark matter E) a dead galactic nucleus that can only be viewed in infrared Answer: C 25) How does the gravity of an object affect light? A) Light doesn't have mass; therefore, it is not affected by gravity. B) Light coming from a compact massive object, such as a neutron star, will be redshifted. C) Light coming from a compact massive object, such as a neutron star, will be blueshifted. D) Visible light coming from a compact massive object, such as a neutron star, will be redshifted, but higher frequencies such as X rays and gamma rays will not be affected. E) Less energetic light will not be able to escape from a compact massive object, such as a neutron star, but more energetic light will be able to. Answer: B 26) How does a black hole form from a massive star? A) During a supernova, if a star is massive enough for its gravity to overcome neutron degeneracy of the core, the core will be compressed until it becomes a black hole. B) Any star that is more massive than 8 solar masses will undergo a supernova explosion and leave behind a black-hole remnant. C) If enough mass is accreted by a white-dwarf star so that it exceeds the 1.4-solar-mass limit, it will undergo a supernova explosion and leave behind a black-hole remnant. D) If enough mass is accreted by a neutron star, it will undergo a supernova explosion and leave behind a black-hole remnant. E) A black hole forms when two massive main-sequence stars collide. Answer: A 6 Copyright © 2014 Pearson Education, Inc.

27) Which of the following statements about black holes is not true? A) If you watch someone else fall into a black hole, you will never see him or her cross the event horizon. However, he or she will fade from view as the light he or she emits (or reflects) becomes more and more redshifted. B) If we watch a clock fall toward a black hole, we will see it tick slower and slower as it falls nearer to the black hole. C) A black hole is truly a hole in spacetime, through which we could leave the observable universe. D) If the Sun magically disappeared and was replaced by a black hole of the same mass, Earth would soon be sucked into the black hole. E) If you fell into a black hole, you would experience time to be running normally as you plunged rapidly across the event horizon. Answer: D 28) In some cases, a supernova in a binary system may lead to the eventual formation of an accretion disk around the remains of the star that exploded. All of the following statements about such accretion disks are true except A) X rays are emitted by the hot gas in the accretion disk. B) the accretion disk consists of material that spills off the companion star. C) the central object about which the accretion disk swirls may be either a neutron star or a black hole. D) several examples of flattened accretion disks being "fed" by a large companion star can be seen clearly in photos from the Hubble Space Telescope. E) the radiation from an accretion disk may vary rapidly in time. Answer: D 29) When we see X rays from an accretion disk in a binary system, we can't immediately tell whether the accretion disk surrounds a neutron star or a black hole. Suppose we then observe each of the following phenomena in this system. Which one would force us to immediately rule out the possibility of a black hole? A) bright X-ray emission that varies on a time scale of a few hours B) spectral lines from the companion star that alternately shift to shorter and longer wavelengths C) sudden, intense X-ray bursts D) visible and ultraviolet light from the companion star Answer: C

30) What is the Schwarzschild radius of a 100 million-solar-mass black hole? The mass of the Sun is about 2 × 1030 kg, and the formula for the Schwarzschild radius of a black hole of mass M is: Rs =

(G = 6.67 × 10-11

; c = 3 × 108 m/s)

A) 3 km B) 30 km C) 3,000 km D) 300 million km E) 3 million km Answer: D 31) A 10-solar-mass main-sequence star will produce which of the following remnants? A) white dwarf B) neutron star C) black hole D) none of the above Answer: B 32) What do we mean by the singularity of a black hole? A) There are no binary black holes—each one is isolated. B) An object can become a black hole only once, and a black hole cannot evolve into anything else. C) It is the center of the black hole, a place of infinite density where the known laws of physics cannot describe the conditions. D) It is the edge of the black hole, where one could leave the observable universe. E) It is the "point of no return" of the black hole; anything closer than this point will not be able to escape the gravitational force of the black hole. Answer: C 33) How do we know what happens at the event horizon of a black hole? A) Physicists have created miniature black holes in the lab. B) Astronomers have sent spacecraft through the event horizon of a nearby black hole. C) Astronomers have analyzed the light from matter within the event horizon of many black holes. D) Astronomers have detected X rays from accretion disks around black holes. E) We don't know for sure: we only know what to expect based on the predictions of general relativity. Answer: E